any Portnoy-era DT album and any Yes album that was released after Talk (Fly From Here being an exeption, possibly even Magnification) What can I say, I always loved all the cover art for both Yes and DT.
Any Led Zeppelin album as well (interesting cover art IMHO, I just never was a fan of LZ and never will be)
Any Iron Maiden cover art (as with Led Zeppelin, I never was a fan of them either but I've always loved their cover art, particulary those paintings by Derek Riggs)