Ralph,
Since your aspiration is toward a "touring motorglider", I'd suggest
you go for a glider rating, but try to get it in a motorglider. There
are a few FBO's that have these, one I can think of is Sky King Soaring
http://www.skykingsoaring.com/ in Sedona, AZ.

The sport airplane "add on" will then be pretty much a "no brainer" as
you will have all the requisite stick time and IMO better airmanship
skills.

-Tom