We've enjoyed every WDW trip we've taken and they've been divided between onsite & offsite stays (some trips included both). The nicest things about onsite (for us) have been:
1. EE... now gone.
2. splitting up and using Disney transport to regroup... possible for offsite people with cell phones and/or taxis now.
3. theme pools with slides.
Only #3 matters to us anymore so we hardly stay onsite anymore. Only the deluxe resorts seem worth it to us and those are so
ridiculously expensive that we only bother when we can get a tremendous discount or a DVC trade (for other timeshares, we own). We like the water parks much more than the regular pool slides so even that doesn't really matter to us anymore.
For offsite, we just love to stay at spacious luxury timeshare condo resorts! The area offers many. They have beautifully landscaped pool areas and the big villas are fabulous. When it comes right down to it, we really enjoy the Florida warmth, the relaxing, beautiful pools, and the comforts of our villa on a nice family vacation. Since this can be found offsite as easily as onsite at a
small fraction of the onsite cost, it's a no-brainer!
The Disney parks are such fun! We like to drive under those purple gateways on our 10 minute drive in. Disney transport is hit-or-miss for convenience and efficiency and we dislike standing on a crowded, aromatic bus (mix diesel fumes with all-day perspiration). We drive our car even when staying onsite (except for MK). Once you enter the turnstiles, it doesn't matter worth a whit where you slept that night. You are at Walt Disney World!!!
We have packages sent to the entry gate area when we shop in the parks, rather than wait to see that our purchases make it safely to our room the next day. We enjoy coffee or ice cream while waiting for the park to empty out at night, whether driving or headed for the Disney transport (standing!) lines. We use Park Hoppers for the best value either way. We use FastPass to limit our ride waits, either way. When spending less for a better room, we may enjoy more meals at the fun, themed restaurants onsite and/or the greater variety of restaurants offsite!
It's a sure thing that a lot of people on these boards get pretty touchy whenever anyone criticizes the "magic" of staying onsite. But as one who's done both, many times, I remind you that the word Magic was aptly chosen... it means "illusion." And all that glossy Disney marketing casts a marvelous spell on many who partake!

The lovely evening lighting, mood music, and detailed design are, no doubt, fun and inviting. But you will get lots of it all day long at the parks too! And some offsite places include similar elements.
In any event, most folks barely spend any time at their resort on their first couple of WDW trips. The parks and some relaxing downtime at the pool will truly fill your stay! Our first few visits were offsite and we had an absolute blast! You will too! So don't sweat these boards. When you go on your vacation, the only people you'll need to please will be your DH and yourself... not a few dozen strangers on a public access bulletin board! Go, stay at the Radisson as you're planning and just enjoy yourselves!!!

Hope that helped!
