lisa,
It's likely that Rick's Italy book would list accommodation suggestions for all five towns.
Given your critieria, I definitely think that Monterosso would be the best choice. The town has two separate parts, an old town and a new town, so it tends to absorb the crowds a bit better than the others. For accommodations, I would absolutely recommend two of the hotels that have already been mentioned, Hotel Villa Steno and Hotel Pasquale. Both are in the old town. Villa Steno is at the top of the old town, and has fantastic views from the balcony off the lobby, as it overlooks the ocean. It's great to sit there in the late afternoon with a Spritz (or whatever) and enjoy the views. The rooms are always very clean, and the owners are wonderful. However at this point it may be very difficult to get reservations in either place, given the fact that you'll be there next week.
If you're unable to get a room in the old town, you could also look at Hotel Villa Adriana, which is at the end of the new town - https://www.villaadriana.info/en/index.php . I've stayed there in the past and found the rooms to be clean and comfortable. It's been a few years and hopefully nothing has changed. They served a nice breakfast, and it has a pool.
Monterosso also has some nice restaurants and Cantina di Miky (by the train station) is a big favourite with many here (including me). Don't confuse that with the more posh Miky restaurant, although that's a good option too.
Two nights isn't much time to explore the five towns, although I suppose a rush visit is better than none. Three nights would be better.
