There are a couple of different ways to go about the Express Pass...let me explain...
Express Pass: These are free passes you can get at a machine for a certain attraction...much like Disney's Fast Pass system. You get to decide between 2 times to return. Downside is: especially during the busy seasons, they run out early...usually around noon or 1:00PM, so going for park opening is key. In addition, you are limited to the number of passes you can get. You can only get one pass at a time, and not get another one (even for a different attraction) until a certain time (will be said after you print out your current express pass), or you use your current pass.
Express Pass Plus: A booklet with one Express Pass per ride. It's good for one person to enter the Express line for each attraction once...with no set time reservations. The downside to this one? The booklet is park-specific. Express Plus for Universal Studios isn't any good for IOA. So say you are a family of 3 who are going to both parks. You'd in the end buy 6 Express Pass Plus booklets. Those can REALLY add up in a hurry.
FOTL: By staying on-site, your room key enables you to enter the Express line. You are not limited to the number of times you use it in the day (however every-so-often they supposedly enforce a limited number for a certain time of day only). The resorts are nice, and allow you to sleep in if you wish....you figure, you don't HAVE to go for park opening if you don't have to 'fight' for the passes or booklets. Even if you stay only one night, you have 2 *full* days of FOTL...even the same day as you check-out.
VIP Tours - VIP Tours are supposedly great, and the best for the "REAL FOTL." However, tours are expensive and may be too time consuming for your schedule...but I can't say this from experience...I've only heard about it.
I hope this helps!
