Not a vacation home, but WestGate Lakes offers some pretty good deals throughout the year that will help with big groups.
I passed up on their 4 bedroom master suite (up to 16 people) for $700 for 4 nights on Memorial Weekend, but boy is that thing huge. I am actually staying in the 3 bedroom instead (up to 12 people).
It is only 3.8 miles away from Universal/IOA (Google Maps). . . and you can just drive up Turkey Lake (avoiding I-4) and be there in under 10 minutes.
It is starting to get a bid outdated, but a solid value and I have stayed there atleast 5 times and I have never had a problem outside of getting close parking when coming in late from a long day. 7 pools, basketball, tennis, mini golf and more is on site.
This is a "timeshare" resort, but if you book through expedia or even through there rental site, they will ask you once when you check in if you are interested in the tour and leave you alone the rest of your stay.