We have family get-togethers for all our birthdays - not individually, but grouping a few together, so usually four or five dos a year. We’re having one this weekend for DS’s (end August) and DD1’s (end September). The dates depend on when we can all make it, and the venues vary depending on who fancies hosting. Everyone gets a cake, usually made by me (I’m having a go at a 2D comic cake this time, so wish me luck). Before the grandsons we’d all go out for a meal, but they’re still young, so for now it’s better for them just to run riot together in one of our houses.
For big birthdays DH and I have in the past hired local venues and invited family and lots of friends, but I’m not sure we’ll do it again. For one thing we have January birthdays, four days apart, so a) the weather’s usually a worry and b) everyone’s a bit partied out by then!