I have only stayed at the Hotel Torbraeu in Munich (enjoyed it very much - great location on the out

Hello all. My husband and I are heading to Munich Sept 2nd for 4 days. We are having a hard time booking the hotels we want, so I have found a few others and would like input. My concern is, comfort, as I have joint problems and will it be hot? (as in no AC in these hotels...)
I have only stayed at the Hotel Torbraeu in Munich (enjoyed it very much - great location on the outer wall just a few minutes' walk from Marienplatz), so I can't comment on the hotels you listed. However, A/C is rare in historic German hotels, and it is unusual to have very hot weather in September, so I would not let that be a deciding factor.
While many tourists like to stay in the Old Town (which is not a bad location after all) that part gets a bit dead after the stores have closed. There are, of course, enough restaurants and also beerhalls to keep you busy and fed, but it's not the prime neighborhood for locals to go out. It's more the area we drag our visitors to (or rather where our visitors drag us to LOL).
"La Maison" is in the central Schwabing district (5min by subway to central Marienplatz), and has a more lively atmosphere than the Old Town. The streets around your hotel are cobblestone, and many small pubs and restaurants are found in any street there. It's a bit of small town feeling there. The English Garden is just 5min walking away.
The "Admiral" is in the G rtnerplatz neighborhood, just a stone's throw from the Old Town (walk less than 10min to Marienplatz). So it's almost like staying bmw and car rentals and denver in the Old Town, but in an area with many cafes, restaurants, quirky shops, and surprisingly few tourists. Actually, it's Munich's most wanted and most expensive neighborhood to live in.
What Dukey said is very true. Early September can still be boiling hot, at least by our standards with temperatures between 80-90F. And when there is heat in summer, thunderstorms will follow one or two days later almost certainly. Therefore it gets much more humid here than in more arid parts of Germany.
If I had to choose between a great small hotel without A/C and a good big hotel with A/C, I'd forget about the Gem tlichkeit and get a decent bmw and car rentals and denver hotel with A/C even if that meant that I had to stay in a more business-oriented chain hotel. Especially when you are not used to sleep at night with an inside temperature of 80F or more.