India. No contest. Most and oldest. Especially south India.

Watch Michael Wood's "The Story of India" on Netflix for why.

India should certainly be considered. Mostly Hindu temples.

Other options: Indonesia, specifically Java. Not only Borobudor and Prambanan, but many others in both central and eastern Java. Both Buddhist nad Hindu. The ones in eastern Java are little visited by foreigners.

Cambodia, Angkor covers a huge area and includes many dozens of accessible temples. Both Buddhist and Hindu, and many that were converted from one to the other,

Burma: The hundreds of temples at Bagan is well-known, but I found the "pagodas" and thousands of stupas near Lake Inle to be remarkable. Unusual Buddhist iconography I've seen no where else. Mrauk U, with temple-fortresses meant to guard the precious Buddha images within, was amazing. The area is closed to foreigners right now. Of course, there are temples in Yangon and Mandalay as well. All Buddhist temples. Many interesting monasteries as well. Some are ruins, but there are many active temples as well.

Laos and Thailand are good for visiting "working wats" where there are monks in residence.

We are temple fanatics. Take a look at our photos at www.marlandc.com Most of the sections have a link to my trip report here on Fodors.

South India is very rich in history and old, but stunning, temples. The Story of India mentioned above does an excellent job of explaining this and would be worth seeing before your trip.

Kathie
Just looked at the pictures on the link in your post. Curious as to what program was used to post these

Thanks

For June and July I would opt for Indonesia and Kathie have described the temples there well. Should have good weather and not so hot or rainy as well.

Thank you so much everyone for your responses.

Kathie, your site is amazing and quite a wonderful resource! I can see what I'll be experiencing when I visit these countries...thank you very much for posting your link!

I am strongly considering south India, Cambodia and Indonesia...hmmm, now just to find the most affordable/safest option.

Thank you so much everyone!

If you're thinking south India you might find the blog of my trip helpful. Start with this post:

http://mytimetotravel.wordpress.com/2010/12/20/into-india/

Actually, for the best temples, start here:

http://mytimetotravel.wordpress.com/2011/04/23/temple-town/

The site was developed in Dreamweaver. My partner is the photographer and site designer.

Johnny, with three weeks, I don't think you could visit south India, Cambodia and Indonesia. South India is the most time-consuming. You could visit a week each in Indonesia (Java), Cambodia, and either Laos or Thailand. By keeping the countries in one area, you reduce costs. All of those countries are very safe to travel in.

It should be a wonderful trip!

In Cambodia at Siem Reap, there are dozens of temples besides Angkor Wat.When I visited in 2010 for 5 days we made it to 7 with a private car/driver and guide. We just scratched the surface. You won't have to change hotels or locations. You can go out in the morning and come back at night and fit in 2-3 temples per day if that's what you want to do.

Thank you again so much everyone for your wonderful tips and suggestions.

Kathie, you're right. I will focus on Cambodia/Myanmar I think.

Susie, I will do more homework on the sites around Angkor Wat!

Thank you!!!

Jonny

We spent a week in Siem Reap and visited 26 temples in the vicinity.

Get a copy of Dawn Rooney's book, Angkor: A Guide to Cambodia's Wondrous Temples