Windsor Hills is only 15 minutes away from Universal. You go out to I4 and you go to exit 75A.
Seaworld is only 5-7 minutes away from Windsor Hills.
You really don't need to be super close to Universal. You will be parking in the Citywalk garage which is closer to the parks than at Disney. Parking will be $12 per day or free if you get an annual pass or park after 6 pm.
If you feel the need to stay onsite, do it. If you get to Universal early at opening, the FOTL perk is NOT necessary this time of the year. We just got back-we stayed at Windsor Hills and used our Uni annual passes. One day we got to Universal at a few minutes after 9. Since the park let guests in early, we were able to do all the major rides (Simpsons, Men in Black 3x, Mummy 3x, Shrek and Jaws) all by about 11 or so. My kids even did the Fievel waterslide quickly which usually takes FOREVER. We did the same for Islands of Adventure and did all rides except the Caroussel and One Fish Two Fish by 11:15. Most rides this past week had 5 minutes or less. In most cases they were telling the express individuals to merge with the regular standby line. Some of the FOTL line people were getting angry-- like I paid more and you're telling me to go in this line.
This does change during the year. Christmas week and spring break time it would be worse, but mid-August to September it is pretty easy to not need onsite. I don't know how bad October is though.