If I want to minimize "RF in the shack" and lightning hazard, what some good ways to ground a transmitter and indoor antenna in a top floor room or attic with no exterior access? (say a multi-story wood-framed building with large non-opening glass windows)
Your solution to "RF in the shack" should be proper antenna design first, and grounding second. See Using a balun with a resonant dipole (or any other antenna, really). If you take care to address common-mode currents, you won't need a ground.
Regarding lightning protection, you might just forget about it. If lightning has struck your indoor antenna, it's already struck your house. You have bigger problems. You can try to provide a path for that energy to ground, but keep in mind: it's a lot of energy, so you need a big conductor. You don't have exterior access, so that means going through the floor. If you don't mind a couple pieces of 6" copper strap running straight through the living room you might accomplish something worthwhile. Otherwise, I'd suggest insurance.
If I want to minimize "RF in the shack" ... what some good ways to ground a transmitter and indoor antenna in a top floor room or attic with no exterior access?
Adding to what Phil Frost said (above), which I agree. Also, you can use an "artificial ground". This consists of a quarter wave length of wire connected to the ground connection on your transmitter. The artificial ground absorbs RF. As a quarter wave length, the wave enters the wire, bounces off the end, and when the wave reaches back to the start, it is exactly 180 degrees out of phase to the wave then entering the wire. The two waves cancel. So it absorbs any RF energy at the tuned frequency. Of course, it works only at the frequency/wavelength that it is built for. You could add artificial ground wires for each band that you operate.