It gets more difficult as they get bigger too! And 1 bathroom for 5 people all needing showers is tough to manage. We only do it for 1 night at a time now and the youngest usually gets stuck on the floor. We bought a timeshare in Fort Myers Beach and have traded around to stay in many wonderful places (Cape Cod, Williamsburg, VA, White Mountains in NH, Sedona, AZ, etc.). We're guaranteed 2 bedrooms, plus a sleep sofa in the living room, 2 bathrooms, full kitchen, dining area, etc. We've been so spoiled by the timeshares that it's hard for us to cram into a hotel room anymore.
We also look for the suite-style hotels - Amerisuites, Embassy Suites, etc. that give some extra room. I also try to find one that offers free breakfast which is a big time and money saver for a big family.
The world is made for families of four

I thought about a cruise, but needing 2 cabins was outrageously expensive! Oh well, DS17 only has another year with us until college so then we'll travel as a family of four - which in itself is bittersweet...