Bloggs,
I guess it must be different today. LAX was my base. In my last two years (88-90) I flew the L1011 to HNL. We were always at MGTOW. Clean climb was around 275 KIAS. We didn't request it, we advised them we were accelerating to 275.
And, in all the types I flew at TWA 280 was turbulence penetration speed below the Mach cross-over altitude. If we were really getting bounced around we would advise them we were doing 280 below 10,000 for turbulence. Never got any static from ATC on that one either. Obviously, we had to hang stuff out and slow down at some point, but usually that was down low enough that the crummy air had diminished.