TWiG,
you ask a very good question there. Personally I don't make many bowls, I've never mastered making them look good and find once you've got one, why do you want another - so hard to sell.
I like to throw colour at things and experiment. I also like to spindle turn so my output is a lot of vases, that works for me, they are decorative and being coloured attract the eye so ladies seem to like them.
But yes I also make to sell, apples and pears, Lace bobbins (since the wife got into lace work) and the various tools, a few goblets, buttons (also started for the wife), knitting dollies and mice (for the children). I also have a thing for re-purposed glass - I trawl car boots and charity shops for glass bowls, bottles or lids in need of the 'other bit' and make it. To the right people these sell very well.