You can ride a road bike without having to bend over. you can just ride on top of the hoods or on the flats of the bars - just make sure when you go to a bike shop to tell them that you want a relaxed non-aggressive position. I think specialized has pretty relaxed geometry on some of their bikes (the ruby), as does a few of the other manufacturers.

I have had a marin and have a marin frame I'm building up now - but I haven't tried the marin that you're talking about.