We purchased 200 pts with the idea of staying in studios 5 days (Sun-Fri) Spring and Fall. (200 was a nice round figure and comparable to what we'd paid for Marriott weeks in the past.)
Then we stayed in 1bedrooms mostly because that was the only size unit left at 7 mos. and then we did an 8 day stay (wanted that in-room laundry). We added on another 120 pts so we could afford the 1bedrooms and/or take family with us in a 2bedroom.
Then we discovered studio use wasn't the dismal experience we feared. Sure there's no laundry but we didn't really use the living room much. And taking laundry to the community laundry room wasn't terrible. But again we got stuck having to get 1bedrooms for a late ressie, so we added on again.
4-5 days I'm very comfortable with a studio for 2 people. You could manage well with 4 if they're kids. Longer than that I'd prefer a 1bedroom.
But in the end it really comes down to a time vs. space argument for me. In studios, I can manage 4 weeks a year. In 1bedrooms, I can only do 2 weeks. If I can travel to Disney those 4 weeks, I convince myself I don't really need a laundry. If I can't, well I can happily afford a 1bedroom.