I live with my Dad in his 18' Schult home(which is now part of Clayton Homes). His mobile was built in 1989, and everything has held up remarkable well. No major repairs or problems - just cosmetic remodeling things. However his mobile has a coated roof and has had to re-coated several times. I think most of the new models have shingles - so this probably would not be a concern. I have looked at our local Clayton dealer and he has several new models that have some pretty sharp looking floor plans. He has several "tag" units which have the living room in a separate section which are really appealing.
I have been told by others on this site that you can obtain better financing rates on a double wides and double wides generally have a higher resale value if you are not planning on living in the home for a long period of time.
Good luck with your search.