I like grilled hot dogs best, for sure, but usually they take careful watching so they don't get charred beyond recognition.
We grew up eating boiled hot dogs for the majority of the year; grilled was only for the summer months when the BBQ was set up. Remember that hot dogs are already fully cooked (you
can eat them raw, like bologna

), so you really only need to heat them through. My mom used to do them in her largest frying pan, out flat, with just enough water to almost (but not quite) cover the dog, then simmer for a little while- 5 mins after the water comes to a simmer maybe? Just roll them around a little for even heating.
A compromise between boiling and grilling would be to panfry them. Put a little bit of butter in the bottom of the frying pan and put the dogs in. Roll them around so they cook evenly- maybe 8 mins total, depending on the heat you use.
I think the "plump" comment was because of Ball Park Franks ("They plump when you cook 'em!" was their ad for years.)
All hot dogs plump a bit when you cook them because the proteins expand. Just don't think about it if it grosses you out! I think Nathan's hot dogs are the skinniest I've ever eaten, but then they taste more like the roll than like a hot dog.
If I was digging out the crockpot, I'd put beans in it, not hot dogs!
