I've never stayed at the Radison, so I can't compare it with HIFS, although we've stayed twice at HIFS and are returning this year. It's a great resort for kids! The free breakfast and the kids eat free for other meals make it a good deal! Having the extra space and three t.v.'s, fridge and microwave is what keeps us going back. The pool area is a lot of fun for kids too.
You could always reserve a room at HIFS and then if you decide to stay at the Radison, you can cancel up to 24 hours before you are spposed to check in.