We plan to arrive in Chamonix on June 28 and spend two nights. Could anyone recommend a moderately priced hotel/B&B that can accommodate such a group?
Are you driving?
I looked up the hotel we stayed in last year on a Rick Steves My Way tour, Hotel de l'Arve, and they seem to have limited availability .
http://www.hotelarve-chamonix.com/en/ It is right beside the Arve River. They have a room for 4 available and say you'd have to add another room or more beds to accommodate your group. The location was convenient and the hotel very friendly. They also have parking, if necessary.
If you are interested, I would call them soon since that was the last family room available. Calling isn't difficult, but you could try emailing, also. The phone number and email address are at the bottom of the homepage.
This maybe a little late for your plans. Le Faucigny right in the center of Chamonix is brilliant for a mixed family group. They have rooms which include two sleeping spaces such as a king downstairs and two twins in an upstairs loft. We visited in September 2017 as three adults and one teenager and once we explained our sleeping preferences, they set us up in two adjoining rooms that fit us perfect. The spa is superb after long days hiking. Great breakfast and afternoon treats. I would suggest contacting them directly by email and explain your bed/ room preferences. They can also be more flexible with room price. Ah Chamonix.......sigh. Breathtakingly beautiful.