I thought I would share my highly subjective perspective on features of the "ideal" event setup.
#1: Separate Event Brackets by Level
Events need brackets for different levels. Lv20-35, Lv36-50, Lv50+ worked well with the Chinese New Year Event. Separate quests prevent frustration from newer, low level players being unable to participate in the event. It also allows Lakoo the ability to have challenge higher level, veteran players. The St. Patrick Day Event combined this idea with the ability for players to choose whether to complete an easy or hard quest. I think the perfect event would have difficulty levels suggested by level but allow players to pick any of the quests but only collect one of them. If a level 55 cannot find a team to do the hard quest, he or she could perhaps solo an easier quest. Also, consider adding an "Impossible?" version of the Lv50+ quest akin the the Halloween Event boss. This option will give the very best players a challenge for a potentially exclusive reward.
#2: Type and Recurrence of Event
My preference is for an event to last around a week or so but allow players to repeat the quest daily. The Valentine's Day Event with the roses highlighted the need for daily rewards. For many new players, the event was over on the first day. More experienced players founds ways to just grind roses to sell for gold and tried to get the elusive rose set over and over again. While many veterans profited from the event, I don't think anyone would disagree that the grinding was just plain boring (even if it was lucrative). The event itself should be challenging and entertaining (in addition to rewarding). I would suggest putting a higher concentration on grinding for the lower brackets with perhaps a small boss at the end. The upper levels grind all the time for copper, chests, and resources. Lv50+look for exciting monster and boss fights from events.
#3: Time and Method to Complete
The easiest portion of the event should take 10-15 minutes to complete. Perhaps farming some items and a small boss fight at the end for a daily reward for lv20-35. This is a fun reward to supplement the path to a higher level. The lv34-lv50, should take about 30-45 minutes to finish. These players are more serious and are stronger. A few mob fights and then two boss fights for two rewards (the last boss being more challenging). Finally, the lv50+ should consist of between 30 minutes to 1 hour to complete. It should have some mobs that encourage teams and a boss fight and then another boss. Break up the rewards so into several pieces so that if people have to leave due to real life the team still gets some reward for their efforts. The Chinese New Year Event did an excellent job at using segments and minor rewards for each part. Failing to beat the end boss was disappointing, but not utterly so since the players were rewarded for what they had done so far.
The most challenging part of event for Lakoo has been rewards for events I feel. Each event needs at least one item that makes players want to participate. For instance, the Easter Event quickly lost attraction for most players after the first day when people realized there was nothing unique to get from the event. Given the simplicity of it, I am not advocating that Lakoo hand out Rose Shields left and right. However, a super-rare chance for a Legendary Red Mermaid (or a Red Rattlesnake or Red Wolf) would have kept people's attention. Something like this should be fairly simple to program with minor tweaks to stats and colors after all. The St. Patrick's Day Event was a good idea to allow poor players the chance to own a 20% fashion. However, I think allowing a very rare chance to get an unbound version of the fashion would have made the even even better. Don't make the rewards too easy to attain but match the difficulty level to the time required. Would you spend 30 minutes grinding mobs just to get some pet food and heals? No (I can see RyuFang saying "Heck No!" right about now)...but alot of people would have if the daily reward had a chance for a unique event item. If you need help thinking of event rewards, create a separate Event ahead of time. Allow players to post ideas for a unique item, pet, etc. based on an upcoming theme you provide. The winner would receive a token sum of gold (maybe 100gc) and one version of the unique item, pet, etc. ahead of time as a reward. Actually, this Event Reward Suggestion system would be a great "filler" event you could run in-between larger events to keep players interested and involved while generating positive feedback in the forum at the same time. It would require fewer resources and provide lots of ideas. Plus, the in-game sneak peak at the reward would generate lots of excitement and comments in the forum.
It is better to create an event that is interesting than one that is just busy work without an adequate reward. I have multiple lv55s in game. However, I would rather have an event that takes and hour and do it with one of my characters than have a simple grinding event that takes 15 minutes and do it with four characters. Longer (or harder) quests with better loot drops are better than easier quests with junk drops requiring multiple accounts to get anything good. The Easter Event would have been a phenomenal event if you had added a third quest difficulty or a unique item. I stopped doing it after a day or so when most of my characters had received a permanent fashion (or two or three). Yes, I know it was designed to even out the 20% fashion but an additional reward would have kept it interesting after the fashion. Try to put yourself in our shoes and make sure if the event is structured like a simple hamster wheel that the cheese we are running for is good (hamster wheel event are ok at times by the way :) Perhaps, select a few long-term, involved players (i.e. like Rhastar2) as moderators in the Forum that you can use for a sounding board for rewards vs effort on events. Many lv55 players could quickly tell you whether a proposed event would interest players in a matter of minutes. It would allow you to customize or make slight modifications before devoting time and effort to the creation of the events so that the they would be immensely more popular on release. It would also create anticipation of the events ahead of time without you having to spend so much time in announcements and updates in forums. Allow moderator volunteers to create topics that are clear, informative, and exciting (while saving you time and effort) about future events.
Hope these thoughts are of helpful! Chime in fellow Lakoo-dwellers with your feelings on the subject!