I understand you want to protect your anonymity, but this is so vague I'm not really sure what to make of it.

Do you mean you are happy to move to a junior base? If so, it certainly gives you more options on which airline you might want to go to. You said you will "be commuting anyway" which would lead me to believe that you are unwilling to move.

Does bunking in a city mean getting an apartment and moving, or living out of a hotel or crashpad during your reserve blocks? I highly discourage you from commuting to reserve for any serious length of time. You are very unlikely to be happy. If the regional you choose is going to be where you retire, I wouldn't be in a huge rush to upgrade. Most captains report that they see a very small increase in their paycheck when they upgrade. The hourly rate goes up, but they go from 90+ hours/month to min guarantee. And you'll be flying. And know your schedule. And have a say in that schedule. And be flying with experienced captains not brand new FOs. Commuting isn't nearly so bad if you have a line, though I'd always recommend moving if you can.

As far as being "close enough" you really need to be within an hour and 15 minutes or so of the airport parking lot so that you don't get yourself in trouble every time you end up in a minor traffic jam if you are going to be on reserve very long. And if you plan to try to upgrade really quickly due to previous 121 time, you're a lot more likely to be on reserve longer than normal.