Although I’ve been buying and drinking wine for awhile, I’m not as knowledgable as most here (although I’m trying to change that), so please keep that in mind with these recommendations:
To begin - For me, $15 is the new $10. I’ve found that there are still many reasonably priced wines available, but if you can go to $15, things really open up.
Here are some suggestions, based on what you say you like:
Marques de Arienzo Rioja Crianza
Ravenswood Vintner’s Blend Shiraz (it’s the Sonoma winery’s label, but made using Australian grapes)
Los Vascos Cabernet (even better if you can pony up a bit more for the Reserva)
Jacob’s Creek Reserve Shiraz (their non-reserve shiraz is only so-so)
Penfolds Shiraz/Cabernet South Eastern Australia Koonunga Hill
Columbia Crest Merlot Columbia Valley Grand Estates
Bogle wines are very reasonably priced. I like their Petite Syrah a lot (although it might not appeal to you), so if that is any indication, then they should be a good deal for the money.
All reds, I know. If you are interested in a white, have you considered a Vouvray? I can’t recommend a particular winery, but I’ve never had one that I’ve disliked (to date, anyway). And to comment on Stranger On A Train’s recommendation for Bonny Doon: Their Muscat Vin de Glaciere is very well respected as a dessert wine. I’ve never tried it, but I’ll be picking it up next month. Just remember that the price is for a half-bottle, so it might be out of your price range.