Radisson Resort Parkway is a very nice hotel and more resort themed. We loved our stay there a few years ago. Its not hard to get to the parks but does take just a few more minutes of travel time. If you think that your parents would like to relax around the hotel and pool, I would have them stay here. Nightly stays here I think run $69 to $89 per night.
However, I have also been to the Grovesnor Resort. If your parents are going to spend time in the parks and don't want to have to rent or use a vehicle, then this is a nice hotel (IMHO not as nice as RRP) for them to be close to the action with a small walk to DTD for fun. The prices for this hotel range. It also occasionally gives up rooms to Priceline for $35 per night, but the lowest that I've seen this hotel recently was $65 or $70 per night a few weeks ago. P.S. If they stay here over a Saturday night, you might want to check into the murdermystery show (about $35 per person and includes dinner, its corny but we did have fun.)
Both are nice places that I would recommend.