Definitely agree - Bukhara and Samarkand are two of the most memorable places I've had the pleasure to visit (and I'm gutted I couldn't make it to Khiva). I'd recommend getting the train or negotiating a long distance taxi rather than braving the domestic Yak-42s, though!

Amritsar's Golden Temple is an amazing place, but I'm not sure there's much more in the city itself to keep you occupied. When I went, I headed over from there to Lahore, the Swat Valley, Peshawar, the Khyber District, and then back to Murree and Pindi via a small town called... Abbottabad. Not sure I'd recommend that journey right now... OTOH, there is the Kangra Valley railway (narrow gauge) that will take you up to Joginder Nagar (you can hop off nearish Dharamsala, too) and from there, you can easily head onwards to Shimla and back down to Kalka. Stunning part of the world.