M.,
Go for it! Scouting is one of the most rewarding activities your boys could do. Cub Scouts is parent-lead and in my son's pack, there were always plenty of families at meetings and events. Even our Pinewood Derby had a division for siblings. The goal was to get the siblings interested in scouting so they would eventually want to join as well (not so easy for girls though since most would rather join cub scouts than brownies after hanging out with the boys). The meetings are normally held at a church although sometimes at local schools but this also means that there's normally a place you can take your younger ones if they get to be too disruptive during a meeting. The church we meet at is very open and lets our parents use the nursery and of course the play ground is always a popular hangout for the younger ones when it's nice out. The meetings aren't normally that late- 6-7:30 for cubbies. My son's scout troop meets from 7-8:30 but since they're older by this point, it's fine with us and allows us to get other stuff done before getting to the meeting. Plus, once they're Scouts, you don't have to stay for the meeting. I normally stay during one meeting a month for council meeting and drop him off the rest of the time (my husband and I were never into Scouts and aren't Scoutmasters or anything).
Cub Scouts typically don't do a lot of camping and when they do, it's usually family camping once or twice a year, however there is no requirement for that. Some boys go with a friend and his family if his family can't go or they don't go until older (4th or 5th grade). After they cross-over to Boy Scouts, then they start doing a lot of camping. Boy Scouts is supposed to be "Boy Lead" though so normally in an active troop with older boys and scoutmasters, you don't have as much "family camping" anymore.
Anyway, my son loves Scouts. Even as a middle schooler with it being socially unacceptable, you'd be amazed at the number of boys who do it- they just don't admit it to their friends that much. Kind of sad if you ask me because I think it's a great thing to be involved in but middle schoolers are very judgemental and they always want to "fit in". At some point most of them grow out of that though.
Good luck!