we stayed at RPR = royal pacific resort. it was beautiful.
while touted as the 'cheapest' on site hotel and ideal for families, we found it to work out amazingly well for us.
we were in a room in the royal tower, on level 3 which was just above ground level.. it was really lovely. our room overlooked a nice grassy nook, lots of foliage and no one around for miles.
the room itself was lovely.. 2 huge beds, armoire with tv, the requisite fridge full of overdraft-fee inducing snack foods and beverages and a table and chairs. our room had a full bathroom, with the vanity on the outside in an alcove, which made getting ready in the morning a breeze, even with 3 adults in the room with their own way of doing things. we had a full size closet in the room, plenty of space to store luggage, iron & ironing board, linen bags etc etc and spare pillows and blankets in the room, which was a bonus.
downside is that you pay a $9.95/day internet fee, or $24 per 3 day block. it's not that uncommon outside disney to pay the internet fee as most resorts/hotels around the area have that fee, or a similar 'resort fee' that encompasses the internet use.
the hotel is beautifully themed, lots of balinese/polynesian influences. we found getting to the parks to be easy breezy, either via water taxi (2 mins) or the walking path (4-5 mins, sometimes this will get you there faster depending on whether the water taxi has just left or not). the water taxis are similar to the 'friendship' water transport at wdw.
the hotel is modern, clean, spacious and well thought out. there are lots of private areas and lots of places to sit & relax without feeling like you're intruding on someone else's leisure time.
in terms of the benefits: front of the line access to the rides is awesome. if you stay onsite, you can use this as many times as you want, including for re-riding the same attraction you just got off... the one you buy has a limit of one time per attraction per guest per day. the one you get for free staying onsite is keyed to your room card, which is waterproof, so no worrying about getting it wet on the water rides... also, this adds to the fun factor for kids (or adults who are really kids at heart) as you don't really have to line up again if you find a ride you want to do again and again. only prob is that you can't use it in harry potter world, and it's not able to be used on some rides, but each ride will state at the entrance which have express pass validation and which don't.
other onsite perk is getting to the park 1 hr before the rest of the plebs (joking

)who don't stay onsite. this is awesome. kind of like EMH but much less crowded and way more beneficial for getting in line for things like forbidden journey or ollivanders wand shop experience.
forbidden journey (if you want to ride) & ollivanders are experiences you must get there early for or else risk waiting in the sun for hours and hours.
forbidden journey has several components... you can do the walk through line (for those who don't want to ride - it skips sections like the greenhouse and the front hall), the ride line (but don't ride, then you get to see/experience the interactive displays along the whole way, and you can take pics of the great hall) or the ride line (where you ride). this is a fabulous experience even if you don't ride (as i didn't). the whole harry potter area is themed beautifully, even more so than areas of disney (please don't burn me at the stake)
if you have any questions, i'm here to answer them.
oh, and make sure you try the frozen butterbeer before you try the regular butterbeer. frozen = awesome. regular = regular bleh. also, get the souvenir mugs. they aren't cheap, but they are great for refills and can be hung from a lanyard or dclip on a backpack throughout the day. also they will rinse them out for you in restaurants. if you want the regular mug, they say 'butterbeer' on them. there are mugs that say 'hogs head tavern' but they can only be purchased by adults 21+ in the actual tavern when buying something alcoholic, and they won't fill them up with anything but alcoholic beverages. if you want the mug but don't want to get it dirty with drinks, you can ask them to serve the alcohol in a to-go cup and keep the souvenir mug nice and pristine.
oh, and yes. universal islands of adventure is not dry. you can buy a refreshing margarita or icy beverage or pina colada or long island iced tea there. it's great... but i don't think many people do, as nobody we saw was drunk or in any way intoxicated or acting like idiots. everyone was very lovely and civilized and respectful.
so yes, ask away