Xfinity is the defacto option, but you need to be in-line 1.5-2 hours before the first pitch if you remotely want a shot of getting in The cover for Game 1 Friday was $20, and there were no drink specials so I ended up getting hit rather hard in the wallet. Wouldn't recommend it, personally. Additionally, they don't tell the line when they cap so you could end up waiting in a non-moving line past the first pitch, for a long time, before you realize your chances of getting in are zero.

Chickies and Petes won't be as bad but there will still be a considerable line. I would recommend also getting there pretty early.

You will probably be able to get into Live! Casino, personally I'm not as familiar with the amenities in there as I don't gamble as much.

If you are planning on tailgating, and want to take full advantage of that without traveling/waiting for these options I would recommend leaving your tailgate 30 minutes before the game and taking the Broad Street Line back up to Center City.

I've been doing this recently for tailgates (Birds/Phillies) and I recommend it over any of the options down there. I don't really want to leave a tailgate early with more than an hour left to wait in line and the BSL is very fast with plenty of trains north.

You will probably be able to get into a regular downtown bar with a more comfortable yet still exciting atmosphere, that's probably cheaper, and without a cover or massive wait for drinks.