ST runs off of ATT so I would get better coverage with their service in my area
Straight Talk has MVNO agreements with all 4 major carriers... Verizon, AT&T, Sprint, and T-Mobile. Which carrier you end up with depends on the Straight Talk phone and/or SIM you purchase from them.
however VM isn't terrible, and VM is 4g right?
VirginMobile (as is BoostMobile) is owned by Sprint and does offer some 4G phones and service plans.
Also, for my son and hubby they stream YouTube and Netflix and I'm reading that isn't allowed on ST?
Not entirely correct. While their agreement does say that streaming is not acceptable, there was a clarification made (cannot locate reference, sorry) that NetFlix/YouTube are standard apps and as such can be used. The issue in reality is that the carrier you ultimately are on may throw an "abuse" flag at Straight Talk if you just suck up a ton of data. Currently this seems to be mainly those using AT&T services and not the others. But of course this could change.
If that's right would VM be a better option?
All of Sprint's companies (Sprint, VirginMobile, BoostMobile) are proud of their unlimited data offerings.
Also, how is customer service and phone choice?
Everyone has opinions. However I'd say that generally you get better service and choices at company stores (Verizon, AT&T, Sprint, T-Mobile) and next best at the company discount stores (VirginMobile, BoostMobile). MVNOs keep their expenses down by offering mostly online/phone service and only select phone offerings. Personally, I've had no need to contact Straight Talk, BoostMobile, or Verizon customer service (have had all 3). Everything has always worked as needed.
We're coming from Verizon but looking to save some money.
Pretty much anything will save you money when you leave Verizon.
Oh, and my son is dead set on an iphone (even though hubby and I much prefer our androids and have tried to win him over); can an iPhone be used on ST at all?
Yes, both the AT&T and T-Mobile versions of the iPhone (when unlocked by the carrier) can be used on Straight Talk. You just buy a SIM card and pop it in. I would recommend the T-Mobile SIM from Straight Talk as those people seem to not get "excessive data use" threats. For you Android fans, if T-Mobile coverage is good enough for you... I'd buy the Google Nexus 4 directly from Google and again, pop in a T-Mobile SIM from Straight Talk (or other MVNO). Personally, I *need* Verizon coverage keep unlimited talk/data, so I had to pick from the Samsung Proclaim or LG Zip. They are the only two phones offered by Straight Talk that run on Verizon's towers. I picked the Proclaim.