...in my personal experience, I usually ride the bikes I own that have tubular rims and tyres way less than the ones with more modern rims and high performance modern clincher tyres.

Just last winter I built up five or six wheelsets to swap out for the tubulars on the bikes that have them. If you go with a a modern lightweight alloy rim like the H plus sons one mentioned, or maybe a Mavic Open Elite (which is bargain priced by one seller on e-bay), and buy a quality high pressure, lightweight tyre in something like a 700x25c, you can get a ride that is not far off the ride of tubulars. It's just a lot more sensible for something that gets ridden because the tyres are more easily repaired when flatted.

Anyway, that's what I do. I have a red early 70's P13 that came to me with what were said to be the original wheels, and they are tubulars. I hardly ever ride it. I have a P15, and the originals on that bike were said to be clinchers. Even in the 70's, very few people were bold enough to tour on tubular tyres.