Mountain bike or Road Bike?

I have a road bike (for what I do I should have purchased a road touring bike instead) and I like it when riding on good roads. I have an older mountain bike and sometimes if the road is going to be a little rough or partly unpaved I like to take it instead. Here is my question: is there some combination or compromise bike that would have less weight than a regular mountain bike yet wider tires than a touring bike? Or, on the other hand, a touring bike that is sturdy and can take tires of a width somewhere between a mountain bike and my 25mm road bike tires? Hope I explained this well enough. BTW, I slightly prefer the handlebars with "drops", but I can live with flat bars just fine.