I'm moving into a house where I can't put up an exposed HF antenna. Any
comments on in-attic antennas?

I have a zig-zag 100' dipole in my 40'X35' attic. I feed it with 450 ohm line
and a home brew tuner. I keep a regular schedule on 75M and 40M with hams 350
miles out to 1000 miles with 100 watts. DX 20M on up. Yes, an attic antenna
will work, and it will work all of you home electronics, as well as your
neighbors, so get ready for that!
73 Gary N4AST