Ok, I guess that's are a lot of towns but I'm happy for any advice you may be able to give.
My brother and I are planning a bike tour next month along the Euro Velo 9 route, starting in Vienna and heading down to Pula in Istria. We've got the Austrian leg of our trip down, where we know a few wine makers who will be happy to house and feed us. Neither of us has been to Slovenia very often or is very well aquainted with the food scene there. My brother knows Trieste a bit and I have been to Istria several times and always found it easy to get very decent seafood there but we'd both appreciate any specific recommendations.
Travelling by bike and wanting to stay within a reasonable budget, we're not going to splurge on this trip. We're looking for places where we can have a simple, local meal and a few glasses of good wine in the evening after a long and exhausting day. And where you won't feel embarrassed sitting down in jeans and t-shirt.