Being from Texas, you will be able to handle the heat!
October is not much different from any other time of year. To be honest, it really depends upon the exposure of the villa to afternoon sun and the steady island breeze. If your villa faces West, you might consider AC for the bedrooms as you might not get them. Check with the rental agency,. If they're not sure...pick a different agency.
We had AC in the bedrooms and never used it, just the ceiling fans.

Coral Bay is a really nice side of STJ, still having some of the 'old island' feel although that too is rapidly changing. With the car, you can access the rest of STJ quite easily.

Thanks Chris @ Work for the info.

I think Chris is pretty much right on in his comments but thought I'd add an alternate view - why we chose the opposite.

For me, it isn't the temps that make me want the AC it's the humidity - I just don't sleep well when it's warm and humid(even though it is cooler at night). Add to that any sunburn and it's not somthing I enjoy. For us, the AC in the bedroom is pretty much a must any time of year but we have never had AC in the rest of the villa and never missed it. We tried without once and I lived but I woudl have preferred to have had better sleep on my vacation.

As for location,the reason we choose to stay closer to Cruz Bay has to do with having a glass or two of wine with dinner in Cruz Bay - we decided that we didn't want to navigate clear cross-island on the switchback roads with alcohol in our system.
We are probably parnoid about this but we just feel more comfortable staying closer to the restaurants we tend to want to go to in the evening.
-aj

Thanks for your views on the subject, yes sleeping was the main problem I thought I might have with no AC. As far as location, I do see your point, but since i wont be bar hopping and wanted a bit more privacy I lean towards Coral Bay even though I may have to drive back if i want dinner out. Very hard decsion though, I suppose I shouldnt be so obsessed with the details but have had vacations almost runied due to bad decisions
(mine) with location and lodging, and since I dont get vacation often, would like it to be perfect, ok,,near perfect..maybe Im asking too much..lol

We just got back from STJ and stayed in the Calabash Boom area in Coral bay and we were fairly high up and did not need A/C. There are some great restaurants in Coral bay. We only when into Cruz bay for dinner once. it was our Anniversary and wanted to try the restaurant 10 Tables. The ride is easy and the views are fantastic.
We loved the quiet side of STJ. Easy to get to the south shore beaches and the north shore beaches.

You will have a great time what ever side you pick. Enjoy!

definitely not not over the top. I know I'm the same way. Good news is that I think it is really ahrd to mess up a vacation on St John 🙂

aj

Depending on rainfall, bugs might be more of an issue in October than heat.