One really interesting thing about staying off-site is that people who do that fall into different categories and therefore have wildly different experiences. There's the hotel crowd (who themselves fall into a few different categories - those just looking for an inexpensive place to sleep, those looking for some resort features like a nice pool, some looking for specific location and convenience (think Downtown Disney hotels and convenience to DTD), some looking for more expensive full-on hotel resort amenities making the experience more like that of a Disney hotel), folks like my family who stay at timeshare resorts, people who stay at one of the many vacation rental communities whether that be in a condo, townhouse or individual pool house. Clearly, that means that the off-site experience is far from being a one-size-fits-all adventure.
When we starting going to WDW back in 1997 (that was about 24 trips ago), our
travel agent found the Vistana Resort (now Sheraton's Vistana Resort) timeshare resort for us and we were overwhelmed at how nice the resort experience was. At the time it was my wife and I and our three daughters (then 17, 15 and 5) and the we expected the trip to be a once in a lifetime event so we went to the Disney parks, Universal, SeaWorld and Busch Gardens, Cocoa Beach and were very happy to come back to a place that was actually big enough for all of us to relax from the hectic pace we'd set for ourselves. The only thing that we regretted was agreeing to go through a supposedly 90-minute timeshare presentation and wasting a morning (the $200 Disney script money that we got for attending was split between our older daughters as an apology for holding them hostage for so long!!!).
I think that the off-site resort experience was a major reason that we ended up going back so many times after that (that and the Dole Whips at the Magic Kingdom!) and I'm not sure that we would have been as anxious to go back if we'd stayed in a Disney hotel (and certainly not if we'd stayed at a regular old off-site hotel).
That experience led to several stays at timeshare resorts via rentals from owners before we bought our first timeshare week at a North Carolina resort (go figure, we were living in New England and just wanted a relatively inexpensive resort week to use as an exchanger to get back to Orlando and other sunny and warm locations).
So a number of people have mentioned a lot of the off-site benefits - more space, lower cost, more amenities, etc., and those are all quite nice - but one that our family has always liked is the escape from the inundation of the theme park experience. I think it's actually pleasant to leave Disney (or Universal or SeaWorld) behind when we head back to our resort. Though, with that said, I'll admit that we really enjoyed our stay at the Saratoga Springs Resort Disney Vacation Club timeshare - a really nice location across the lagoon from DTD and we got to see the DTD Fourth of July fireworks up close (don't think they do that anymore). But even during that vacation we rented a car and usually drove to the theme parks. [Disclosure: I enjoy driving and the freedom that having a rental car gives me and my family to go wherever we decide to go during our weeks away from home.] Orlando in general and the Disney property specifically is easy to navigate in a car so I've never found any particular stress in driving around the area - even in the pre-GPS days when I'd gotten us a little lost on occasion. The bottom line is that, for us at least, having a rental car is a must and one with a convertible roof is always a nice bonus.
I'd suggest that if you've experienced on-site and liked it but have even the remotest amount of an adventurous attitude then going off-site will be just fine. It's not the same, you have to make adjustments particularly in terms of transportation that you wouldn't have to make on-site but the trade offs are pretty impressive depending on your reasons for staying off-site. And there are a lot of lodging choices in the area. Depending on where you end up staying you may well find that the change is well worth it and you may be delighted that you tried it.
Enjoy!
Dick Taylor