Thinking of planning a group vacation with old college friends and their families. All adults in late 30's to early 40's. Kids range from diapers to teens.
Anyone with any experience with this?

I'm leaning towards a lake house(s), in the eastern half of the US.
There are potentially 4 - 7 families, with a possiblity of up to 30 people, and might need up to 14 beds, as some of the kids are only children, or are older boys who do not like sharing a bed.
Any suggestions?

A lake house is a good idea for getting everyone all together BUT...this type of trip tends to be a lot of work. There is cooking and cleaning, not to mention keeping the kids occupied.
Consider either a cruise or All Inclusive resort vacation. With this type of trip you'll generally know what your costs are TOTAL up front. Sometimes renting a vacation house looks cheap on paper but then start adding up costs like food, drinks, entertainment and your cheap getaway isn't really that cheap anymore.

With a cruise or all inclusive resort, there will be plenty of activities for ALL age groups including plenty of together time for everyone and even babysitting for when the grown ups want some time to themselves. Normally with 8-10 cabins/rooms you'll even qualify for a group discount.

Hhmmm...
Someone from our party had suggested an all inclusive, and I hadn't even considered a cruise, because I would have assumed that either one would have been too cost prohibitive for some of our families. Perhaps I will check into those options to see just how expensive they would be.
Thanks!

Just remember to get the soda pass... each of the lines offer them, but all have different names. Basically you pay one fee and get endless refills on soda throughout the cruise. I am old enough to drink, but I bought it and used it plenty. It was great being able to just grab a drink by the pool without worrying about the cost adding up.

That is the biggest things about cruises, yes technically everything is included, but drinks, shore excursions, etc. add up and they add up quick! Doing your research will help keep those costs in check!

Thank you! I didn't know about that.

Two extended family members have already claimed that they will never get on a cruise ship. Both have a fear of not having land in sight, and goodness knows what else. Neanderthals!

My own family is sold on the cruise idea, so we may well end up going anyway, without any extended family members.

I think one of the main goals of such a gathering of family or friends is to create an environment where quality connection can happen. This is more likely if people can't spread out in too many directions and don't have distractions like TV's, etc. Also, sharing a common activity can really create bonds. You might thus consider something like a rafting trip. These last from a day to a week and can be mellow or very exciting. They are available in many locations around the country. A guest ranch would be another idea, or a place where you rent cabins and there are outdoor activities to do. The beuaty of a shared activity is that is gets everyone into a new environment and builds community and connection. Many of these sorts of trips can be "turn-key" packages, thus saving you a lot of logistical planning and effort. A package option also has the advantage of being less stressful as decisions are made and knowing up front what costs will be.

Petergrubb had a great point about a family vacation not having any distractions! One thing you might consider is a dude ranch, they are great for family reunions and get-togethers. Three ranches that I know of don't have any TV's in thier cabins! The rugged mountain ranges of Colorado are great for family bonding... and there are all kinds of activites for three-year-olds up. A great website with a lot of info and a huge list of ranches is www.cdgra.com. I highly reccomend these little known bits of paradise!