Universal does NOT key the room keys as in-park tickets. Up until last year, they would use your room key as your unlimited Express Pass. Now at the hotel just after you check in, there is a kiosk you use that will take your picture and give you an Express Pass ticket. (So now you get to carry around your room keys, your park tickets AND your Express Pass tickets.)

Its been quite a while since I last purchased a whole vacation package from Universal Studios. They used to have some good package prices (pay for 3 nights, get 1 free, etc.), but over the last few years, I've not seen any good package deals that would make it worth while over getting a good hotel discount.

Note that depending on the number of days you will be staying. You might want to check out the cost of the Power Pass (annual passes). These do have some black-out dates, but there aren't too many and they may work very well for you.

Another option is to look at what type of hotel discount you can get with the Annual Pass discount. Those can sometimes offer some very nice discounts, but to get those you also tend to have to plan fairly early (as they can run out of those discounts fast.) This would also be a benefit of getting an annual pass. (This discount though requires at least one person in the group to have the full or Premium Annual Passes, not the Power Pass.)