For penetrating builds and cruise ships, DTR and DLR radios are the way to go.As N1DAS mentioned, I'm a big fan of the DTR/DLR radios like he is. Depending on how many radios you need, they are definitely not going to be cheap. But you are going to get some very good performance. In some of my testing, I have gotten over 20 miles line of sight in the desert, flat terrain, with no obstructions. Don't for a minute think that's normal. I have the luxury of open, flat desert here with basically no obstructions, but under those same conditions, there is NO WAY a pair of MURS handhelds or GMRS handhelds will make that trip. I tried it. Epic fail. Going on a cruise? Full ship coverage with the DTR/DLRs is commonplace.
There's also something to be said for the crystal clear audio. No static at all, and if your radios are configured properly, you will never have to worry about interference from others, or people listening in on your conversations.
But again, all that said, you are not going to be spending $15/radio. They might do the job just fine for you.
For operating outdoors and dealing with some terrain/hills, MURS would be the way to go.
GMRS/FRS would work too at a camp site but is more likely to be crowded with kids on bubble packs if it's a busy camping area.
The DTRs and DLRs do very well on cruise ships. Many people report full ship coverage compared to a pair of 4W UHF Part 90 portables on GMRS which had trouble penetrating more than about 2 decks. That exactly matches my experience on a cruise a few years ago but I didn't have any DTRs or DLRs to try back then. When deep inside a cruise ship, you are essentially inside a compartmentalized metal box. Like with buildings, the ship is much more "open" at 900MHz compared to GMRS and MURS. The shorter wavelength signals at 900MHz tend to reflect in and out and around all the nooks and crannies of the ship where longer wavelength signals won't, similar to how UHF and 800 are bands of choice in cities. I would expect MURS to be almost unusable when deep inside a cruise ship. Given that you are operating inside a complex metal enclosure, there are a lot of reflections created and they actually can help at 900MHz. At any given location, what may be a dead spot at one frequency may be a hot spot at another frequency. The hot spots and dead spots move around as the frequency hops at 11 hops per second. The DTR/DLR's FHSS operation effectively stirs the modes and actually helps with coverage.
I think MURS would be a good way to go for the camp site and not have to spend lots of money.