Well, there are actually very few gear 5.12s at the BRG that will prepare you for the Valley in terms of either pure jamming technique or subtle granite smearing, but here's a good list, from what I think is easiest to hardest:
Big Top, 5.12a, Lower Meadow River.
Great gear, but very little jamming; the crux was a layback for me. Still, great, and probably the easiest trad 12 at the New. Traverse in from the left, unless you want to add a 5.11 r/x start.
mountainproject.com/v/big-t…
Fingercrack in White Corner, 12a, S.Nut
Easier and more straightforward moves than The Beckoning, but WAY pumpier!
mountainproject.com/v/finge…
Genocide, 12a, Beauty Mtn.
Obvious fingercrack on the far left of the Disturbance cave. I have not yet done it, but have heard the crux is the pumpy face up to the crack, and the crack is mid-11 or so.
Stolen Tiggers, 12b, The Other Place (Meadow)
Bolted start, but this is still my favorite roof crack in the area (only because I can't do Greatest Show)
mountainproject.com/v/stole…
Portly Gentleman's Route, 12c, Fern Buttress
Fairly easy crack and roof climbing to a stopper 3 move crux. Do this if you are feeling v-bouldering strong.
mountainproject.com/v/portl…
Black Crack, 12c, 1st Buttress, Meadow River
Really nice Peter Croft route that doesn't get done that much, since it sits right in between a couple of popular 13a sport routes. Easier finger crack and face climbing, to a heady but safe riht traverse, into a killer steep hands and finger crack. Take way more yellow tcu/.4 camalot size than you need.
Luv Nothing, 12c, S.Nut
My personal favorite. Pure, steep thin hands and ringlocks jamming. A bit of wide choss that the bottom, and you may want to haul up a stick to clean out the spider webs at the bottom alcove.
New Traditionalist, 12b, S.Nut
Unless you have tiny fingers, this may feel like solid 12+ to you. Way quality, though.
For Yosemite prep, I would get on Luv Nothing and Black Crack, as well as the classic 11s like Chasing the Wind, Agent Orange, Stuck in Another Dimension, and Leave it to Jesus.
Enjoy!