Need B+ MPG, deciding between B & B+

I'm torn between a B and B+. I'm worried about the bathrooms in the B, not much room to say the least. I love the bathrooms I've seen on the B+ models. I can't decide if it is worth giving up mpg for the extra space in a B+. This will be our (2 of us) first rv and want it to be the first and last. Our main goal is travel and sightseeing, but once we retire we may want to live in it for a month or two out of the year in a warm climate. This forum is so great to bring up concerns you don't think about. The other day one mentioned the size of the holding tanks. I really hadn't given that any thought but I sure will now. Thanks everyone. You get so much more information on here than you do from salesmen!