Hi RM - such things are very common in my world. We only meet monthly, but last Sunday 3 of us went out to lunch and on on 5 May we all went away together. Lodge trips away are always good. Friday week, we (and the ladies) are all heading out for drinks at the pub.
Without creating cliques, a trick is to organise small groups, even if you and your wife pick another brother to go out to dinner with (it has some to pass that our girls call each other and arrange a date, then invite us LOL). Small groups are nimble and can be age and interest appropriate, but don't make them closed events so anyone can come. We crossed the bay on a ferry with 2 ladies with us and one of our 90 year olds, but the main group was in the 30-40 year old age bracket.
Another good way is just find something you want to do (movie, sports event, festival) and say you are going and throw an open invite out for others to join you.
The trick is creating opportunities for friendships to be born and nurtured, one of our good ones for that is the annual working bee on our building - one year we had 27 turn up and the lodges here are small (30-40 members).