They say free advice is worth the price you pay for it, and since I have no personal experience, take it fwiw.
At least as some point in the last few years, I've heard some regionals are asking you to sign an employment contract, which would prevent you from quitting for your target major. Just make sure that's not part of the deal to get you a free ATP.
Also, I've heard there is huge variance in QOL at different regionals, so ask around too. And you won't be the last 20 year non-recent/current mil guy to have to do a quick pit-stop at a regional to get 100 hours of recency to be competitive at a Major. I've got an O-6 buddy in exactly your shoes right now...
Anyone else have more recent experience?