A lot depends on the relative merits of the B&B themselves. Dunquin is the more spectacular setting but being at the end of the peninsula is not a great base for exploring outside of Dingle. It would involve a lot of long drives. Valentia while not as spectacular itself is really beautiful, is close to the Ring of Kerry and the Skellig Ring, It's also right next to Portmagee and the boats to Skellig Michael. The spectacular Cliffs of Kerry (better than Moher) are a stone's throw. Wonderful small villages abound.....Knightstown, Portmagee, the Glen, Ballinskellig, Waterville, Cahairdaniel, Derrynane, Sneem etc. Insane scenery on the Skellig Ring and on the south side of the Ring of Kerry. There are Abbey ruins, ring forts, standing stones, castles, famine homes, beaches and Best of all a quiet wonderful area. Plus from Valentia there are ferries that can link you easily to other areas.
You wouldn't go wrong with Dunquin .... it's beautiful, there are villages and historic sites. I personally prefer the Skellig Ring area better.
Many B&B 's and cottage rentals charge for those things. It's usually a modest set amount. We've never been ripped off but I'd confirm the amounts beforehand.
Driving is so individualized but I really enjoy driving there. If you take your time, know that estimated driving times are wildly optimistic (double to be safe) it is safe and enjoyable. Make sure you get ALL insurance coverage, especially tire and windshield.....it's super easy to scrape a tire etc. I'd also recommend an automatic....it's worth the price.....shifting with the "wrong" hand is not fun on narrow roads at speed. That and have a good calm navigator who can calmly remind you to stay to the left ! Actively encourage backseat driving. Driving yourself, setting YOUR pace and picking your interests is vastly preferable......but tours are a fine option. I'd hire a private driver over latching on to a tour bus if you do go that rout.
You can't really go wrong. Ireland IS magical if you give yourself quiet time, don't rat race to try and see everything.....and take time to Really interact with the amazing people. Finding a great cafe, having a scone and talking with the owner/baker is every bit as wonderful as seeing a big tourist site, better even. We are reserved folks but the Irish people have teased us, laughed with us, invited us into their homes and made everyday encounters treasured memories.
You are doing everything right...picking a couple spots to really immerse yourself in and NOT flying around the country trying to see everything and in the process missing most of it. Have a great trip ! Either spot works but my vote is for Valentia !!!!!