Hey I don't think it's necessarily your tires that's causing the flats.... Maybe it's the way your riding? I'm 265 and I've been running the same 23c's since winter and I love them.I used to ride wider tires because I thought wider would always be better since I'm heavy. But I've found I can run any sized tire with no problem if it's inflated to specs and I shift the weight on my bike so that all of it isn't on one tire. It can also depend on your riding style also do you jump off or curbs? Is the road uneven where you ride?

When you install the new tubes, put a little baby powder on them: This reduces friction between the tube, tire, and wheel, which can help prevent flats.

this would just create a mess.

In mountain biking, this is the poor man's Stan's (tubeless system, allows lower pressures). Yeah, it's a little messy, but reduces the likelihood of pinch flats.

You probably just got a puncture. Most of the time the object doesn't stay stuck in the tire, that's why you didn't find anything.
By all means get some Velox rim strips. They come in different widths so measure the width of you rims before you order. A cheap alternative that works well is glass tape.
The best tubes are the cheap ones. The more expensive tubes are lighter and weaker. Walmart tubes should be fine.
I have found that Slime does not work well at 100psi.
Also, there are things called tire liners (Mr. Tuffy) that go between the tire and tube that don't let things poke through. They come in different sizes according to tire size.
The Vittoria Randonneur is the toughest tire that I've seen and will outlast ordinary tires 3:1.
Always buy 3 tires at a time. The front will outlast the rear 2:1.
Nashbar usually has good deals on 700x38 tires.

Well BikeTiresDirect forgot my velox... so I am still yet to be able to see if I continue getting the flats. Worst part is that I used 2nd day shipping on my actual order and now they are sending it economy... Ya for waiting another week to be able to ride... UGH

Got my velox today! finally... Man the difference between the velox and the cheap horrible plastic ring that came on my rims is phenomenal. I dig having the fattie (35c) in the back. I rode probably around 7 miles today. I even purposely took a harsh road to test out the new tubes/tire/rim tape. I am pleased to say that the tire held its pressure. I really think the Velox was the game changer, thank you so much for recommending it.

This is actually a very good idea. A little goes a long way.