Do you mean the song?

It gives you the whole Zeppelin experience. I think maybe II is as good, but the breadth of styles on HOTH is greater.

Don't worry about it. I'm here for the long haul.

You seem to know a lot about the ambient genre and Eno-related stuff already. I'm not sure there's a lot people will be able to suggest that you aren't already aware of. However, I'm going to try anyway. I think you'll enjoy some Krautrock and modern low-fi indie.

Cluster & Eno - Cluster & Eno (obviously)

Neu! - Neu! (a little groovier than Cluster)

Tangerine Dream - Phaedra (a little darker)

Broken Social Scene - Feel Good Lost (this is their first album and is mostly ambient, different from their others)

The Books - The Lemon of Pink (more low-fi than Eno, but has a similar vibe)

Try Aphex Twin's Selected Ambient Works 85-92. It's a little beatier, but there's an obvious influence.