I've only been to Universal twice, so I certainly do not have the level of expertise that many others have, but this will at least get you started!
There is a combo ticket that offers admission to Universal, IoA, SeaWorld, Aquatica, and Wet & Wild. It's valid for 14 consecutive days and you can visit multiple parks in day (I would equate it to a Disney 14 day, Park Hopper + Waterparks ticket). Cost on undercovertourist is currently $247.95 for adults, $227.95 for kids (3-9). You can buy now, but not "activate" until next year. Don't expect these prices to go down.
We haven't gotten the meal plan before, but we have stayed on the club level because we enjoy the complimentary, continental breakfast each morning. Prior to leaving for the parks, we'd stop in the club to pick up bottled water to bring into the park. The meal plan also doesn't make sense for us because it involves in-park dining and our pattern is to go to the parks for a few hours in the afternoon, each lunch somewhere in Citywalk (lots of options), and then hang out by the pool in the afternoon. Prior to going out for dinner and back to the parks, our hungry teen boys would often make another stop in the club for soda, fruit, or other appetizers. This helped to keep our food bill down as well!
We usually combine our Universal trip with something else in Florida (i.e. Disney, Tampa, or a cruise) so we've only spent 2 1/2 days there. This has given us plenty of time to ride everything we wanted many times, and also has allowed plenty of downtime/relaxation in the afternoon. This year, we will be spending 3 full days there because of Harry Potter, but if we hadn't been before, we would probably look at bumping this up to 4 days. I should mention that our kids are pre-teens & teens so they are into all thrill rides (and go multiple times).
To us, there is a definite difference between a Universal/IoA trip and a Disney trip. I think the action in the parks in Universal/IoA is a lot louder and more spastic. It definitely does not have that fairy-tale, sweet essence that Disney has. It does, however, have a huge fun factor. In addition, FOLT priviledges just cannot be beat. The longest we have ever waited was about 20 mins for the Simpsons, but most rides were 10 mins (this is in early August). So, while there are still waits, they are pretty minimal and there is no "Fast pass strategy" involved.
IMHO, staying onsite at Universal/IoA is far superior to staying at a Disney resort. You simply do not need to get into a vehicle or on a boat to get anywhere at Universal (you can take a boat ride, but you don't need to). Ditto for dining and I think the restaurants in CityWalk are much more reasonable in terms of pricing as well. In addition, getting back to your resort for an afternoon break is hassle-free. No hopping on a bus, boat, or finding your car...just walk!
Again, hope this provides you with some information, but others have much more experience than we do and will be able to answer all of your questions!!
