A good question and one that has about as many answers as respondents.

Several folks here have said it best, wear the tartan you like (as long as it's not proscribed, and most aren't) and make the effort to learn a bit about the family or region it represents.

My folk likely came from lowland Scotland, ended up in Virginia at the end of the 17th century and have no tartan of their own. I could wear general tartans and there are several I'd love to have.
However, I've chosen to have our own M.A.C. Newsome (http://albanach.org/) design a tartan for my surname to honor my ancestors. It will be a 'personal' tartan and as such will be available for any to wear. As the 'owner' of the tartan, I'd be honored if anyone had a kilt made in it and learned a bit about my family. I suspect most clan chiefs feel the same way.....but that's my opinion.

Enjoy!