You'd think that my dad and I would be the non-adventurous ones the family would take. But despite my disability and his 76 years, we get along famously with the aid of our personal powered vehicles. (He uses an
ECV and I have a souped up powerchair.)
We do Disney at least twice a year for a couple weeks. We have the APs and have done the commando touring on NYE till 4am at MK. In short, we tire out all our younger, healthier guests.
Now we've taken complete Disney virgins and those with some experience. We've had control freaks, whiney terrified youngsters and daredevils. How the trip goes and what itinerary you make depends entirely on your guest's personality. We usually give ourselves wrap-around time to detox in Disney without the guest. Keeps the blood pressure down when your guest doesn't behave the way you envisioned and/or you have to sacrifice on your plans to make them happy.
With the "slow pace" guests we usually concentrate on only a few things we know they'll like. If dining and scenery is their thing then we take them to EPCOT and Animal Kingdom (or just AKL/AKV if walking is a huge issue). We may also take them to Magic Kingdom one evening just to get a feel for "Disney" and take in a fireworks and evening parade. MGM/DHS can be good for "slow pace" guests as long as you stick to the shows: Beauty & the Beast, Indy Jones, Backlot Tour with museum, Animation Studio. The car stunt show is fun but very loud. It can be overwhelming.
Whiney, scared kids tend to do well in Animal Kingdom. The animals have a calming effect and are not overwhelming. Avoid the 3D shows and thrill rides.
Best thing I did for my sister's family was to give her a kidless day on her anniversary. I took her boys to AK and she and her husband went to EPCOT for F&W. We all had our own fun.
Of the two solo adult newbies I've taken, perhaps the most fun is had when you have someone who's willing to trust your guidance and eager to try anything. Took my cousin last year for NYE and he was game for anything. Even parks at 3-4am. But we also only went for 3 days. Even I had trouble doing the commando touring for that long. When I took another friend a year before we did 7 days and I tried to show him everything. Lots of commando touring, very little rest, and we were all exhausted. I learned not to take too big a bite the next times.
For the grand gathering I'm planning next year, my dad and I will do our own itinerary and be flexible to stragglers. The 15 people going with us have been to Disney before, though not all as much. We have to resist the temptation to show them everything. I know if we try it'll just lead to confusion and fights.