On a recent trip, I almost stayed in Strasbourg but decided to see it for a few hours during the day off the train and spend the night in Colmar instead. Hotels aren't cheap in either town. (Or Paris for that matter.) My one hotel suggestion for Strasbourg is: book something early in case the town books up due to European government business (though probably not in August).
For Paris, you need to figure out first which area of town you want to stay in (or pick a few areas) - and that isn't something anyone agrees on, even people who have been to Paris many times. Paris is huge but easy to get around by metro train and by bus. You may need to compromise between hotel location and price, depending on your budget. Are you the type of person who wants to stay in a lively area where you can walk from your hotel to fun restaurants and shops? Or would you be OK being further from the action and taking public transportation to get back to your hotel in exchange for saving some money?
Last time I stayed in Paris, I stayed in the Opera area, in the 2nd arrondissement (section of town), because I got a great hotel deal there. It was convenient to sites and Metro but I didn't particularly care for the immediate area (I didn't attend the opera, though). Once I stayed near the Eiffel Tower, something some first-time tourists might prefer, but it's...touristy. I think I liked staying in the 17th arrondissement best, years ago, because it's more of a nice residential neighborhood - not much of interest to the average tourist, though, I guess.