majorlu,
It really depends on what you're seeking. Personally, I prefer the Radisson Resort Celebration -- I generally prefer upscale, deluxe, full-service hotels. Room service (here's a tip: always ask if they offer a children's menu, then order off of that... prices are generally inexpensive and portions are quite satisfying) and poolside drink service are amenities that are important to me. The Radisson also offers a superior pool area, with plenty of activities (like volleyball, etc.) It's also a unique hotel with beautiful grounds, as opposed to the Springhill Suites which might as well be Springhill Suites Gatorscreek GA. I also like the location -- easy on, easy off the freeway as opposed to Springhill which can be a pain-in-the-butt to get in/out of (especially when Dixie/the mall closes/etc.)
That said, the Springhill Suites is a very nice hotel. It's also 25-30 years newer than the Radisson (although I think the Radisson is just fine... I've very picky about where I stay usually preview multiple rooms before I find one to my liking -- that's true no matter where I stay). Give the time of year you're traveling at, you'll probably have to arrive at the breakfast area as soon as it opens in order for it not to be picked-over (it gets crowded quickly!) But the room arrangement (2 beds + sofa coach & 2 tvs) is probably more comfortable than the Radisson.
I'd compare the TOTAL prices of both properties, including taxes & fees (remember the $10+tax "service fee" at Radisson) at both properties, then calculate that against the amenities I desire. Also, I don't know where you're booking at most websites (including Radisson's own) allow you to add on two breakfast buffets for $10/night which is a great bargain (you can add additional for $10/night, which includes the additional person charges... the buffet is like $13 direct so it is a small savings).
Also check land-only vacation packages via US Airways Vacations and Funjet (sometimes United Vacations, which utilizes Funjet, offers better pricing). Keep in mind that Funjet/United includes resort fees (plus they throw in Gatorland admission for free for your party) whereas US Airways does not. These websites generally have great prices on these two hotels, but X-Mas may be picked over depending on your dates.