I would stay in Center City but park in a cheaper lot nearby (not hotel parking) and use cabs/lyft/walking to get around.

What do you want to do? For historical sightseeing, Society Hill or Washington Square or a hotel near City Hall would be good. You really can't go wrong in Center City. All the suggestions given so far are good.

I wouldn't stay on the main line without a reason. You could take the train in, but it seems like a hassle if you have the option of staying in the city.

I just stayed in the Sheraton Society Hill and it was very nice and in a great locations for sightseeing and some really good restaurants.

We are staying in Marriott Downtown, in the tower. This is a great location if you love food. Across the street fromReading Terminal. Downside is that their pool is closed for renovation.

what are you planning to do in Philly, that would help narrow things down

We went to Philly in January for a history-focused trip. We stayed at the Hotel Monaco, which is on Independence Mall. Did Independence Hall, Carpenter's Hall, the Ben Franklin site, Museum of the American Revolution ... all of which are in Old City and therefore walkable from Hotel Monaco, which was why we chose that hotel (although there are others in the same area).

We are going to spend a few days in Philly next week. Hotels and AirBnB are plentiful. Can anyone recommend a neighborhood or town we should consider staying in? I'm getting overwhelmed. We can drive into the city if we stay out in a Main Line town. Our boys are 9 and 13.