Favorite destination in the Czech Republic?

I have many. Aside those mentioned in Rick Steve book: Prague and the Czech Republic let's mention spa towns Karlovy Vary and Marianske Lazne. Nice to walk around, soak the ambience, drink mineral water, have some massage and bath and they are also pretty towns. Pilsen famous for its Pilsner Urquell Brewery. What's also interesting to us is that it's the largest Czech city liberated by American Army (other cities: Ceske Budejovice, Karlovy Vary and many smaller towns). Most of the towns of South Bohemia (western part of C.R. is called Bohemia, eastern part Moravia) Rick mentions just two: I add Ceske Budejovice (german name Budweis) where the original Budweiser is brewed. IMHO tastes much better than the one from St.Louis. Tabor founded by religious rebel group Hussites (first protestants- about hundred years before Luther).
Pisek with the oldest stone bridge in C.R. Jindrichuv Hradec with a nice chateau. Pelhrimov- beautiful historical square and streets around. Probably one of my most favorite is a region called Slovacko. Located in southeastern Moravia, it is the most traditional region of the Czech Republic. It has the most folk songs completely different than in Bohemia and even west Moravia. Now almost every village has its own dulcimer band. It is also a wine region. Especially white wine is very good. Most folk songs are of course about love. But the second most about wine. Then about horses and wars with Turks (they occupied Budapest for about 100 years and tried to conquer Vienna without success). There are also songs about famous Austerlitz (in czech Slavkov) battle. In certain subregions of Slovacko there are also so called zbojnicke songs. Zbojnik means forest robber or outlaw, I would say something like moravian Robin Hood. What to visit: the main town of Slovacko: Uherske Hradiste (literal translation: Hungarian Fort. It was founded as a fortress against raids from Upper Hungary). It's a pretty historic town with two main squares, several churches, Slovacke Museum, a lot of wine bars, cafes. Railroad station was voted as the most beautiful in C.R. Street with wine cellars in part of town called Maratice. In neighboring Kunovice (get there by city bus) you can visit Flight Museum and take a sightseeing flight. What else to see there: nearby Velehrad basilica, castle Buchlov, chateau Buchlovice, Straznice with its chateau and large park and skansen and museum of southeastern Moravia. Nearby are famous wine cellars: google Petrov Plze. In Slovacko there are many folklife festivals. To mention just few: Ride of Kings in Vlcnov May 23-25th. Traditional mowing of grass by scythe http://www.malavrbka.cz/ on June 14th early morning start. Once you have the website, click on pozvanka. It is in Czech, try translator or send me pm and I translate it for you.
Mowing in Buchlovice chateau park on June 1st. International Folklife festival in Straznice June 27-29th. Hornacke slavnosti (festival) in Velka nad Velickou 18-20th July. IMHO most authentic. Ozveny (Echo of) Hornacko also in Velka August 16th. The largest festival is festival of wine in Uherske Hradiste September 13-14th.
http://www.slavnostivinauh.cz . More information about smaller local festivals you should be able to get in Visitor Center in Uherske Hradiste located on the main square (Masaryk) next to the church (on the right side). It's the only visitor center I have seen where you can buy wine. Useful website:
http://www.czechtourism.com/a/slovacko . Among others I am planning to visit some of these festivals this year.

There was some date change of one of the festivals: so I edited today 05/09/2014: Traditional mowing of grass by scythe - there is a different website and different date.

I really enjoyed the brief visit we had toČeský Krumlov. It's a small town, and you can get around it easily. The castle is lovely, the views are wonderful, the river is picturesque, the food is good and we really had a good time.

Prague was so very, very hot when we visited in July. And, it was unbelievably crowded. The Charles Bridge reminded me of Times Square. And I now live in NYC and like most New Yorkers (oh my, did I just call myself a New Yorker!) I avoid Times Square like the plague. I travel beneath it on the subway. :) I think that Prague would be lovely at a different time of year.

Pam

I deliberately did not mention places which are in Rick Steves book. Most first time tourists in C.R. visit Prague and Cesky Krumlov. And there is reason for that. Both are very picturesque and fairy-tale towns. One big, one small.

I already wondered how many people could answer here without mentioning Prague and Cesky Krumlov... :D

Here is my list:

Adrspach-Teplice Rocks
A very small region close to the Polish border with very picturesque rock formations.

Svatý Petr (St. Peter)
This is a part of Spindleruv Mlyn in the Krkonose mountains, in the former Sudetenland. Unlike in many other parts of the mountains, which were more or less turned upside down after WW2, you can still get a sense of the old Riesengebirge (the German name of the mountains) in this little village.

Marianske Lazne
One of the three famous spa towns in Northwestern Czechia. Not as famous, big or glamorous as Karlovy Vary/Carlsbad... that's why I like it more. And you don't have to speak Russian there... :D

Tabor
One of the many small, preserved towns in the country, and very important for the history of Bohemia.

Telc Basically just a huge town square and not much else, but this town square is one of the most beautiful in Central Europe.

Without mentioning Prague as the answer to the question, I would say Pilsen, the only other place I've visited in CR...so far. Yes, the "American Monument" is not very far from the train station, walkable. In the summer of 2001 I took a day trip r/t from Nürnberg to Pilsen, then still by train, saw the American Monument, as pointed out above. It pays tribute to the true liberation of the city by Patton's Third Army, which was under orders to stop advancing at Pilsen. The train station's architecture is interesting; hopefully, in the last decade it has been refurbished. CR has numerous fascinating places to see, Brno, Slavkov, Benesov, Hradec Kralove, etc.

Olomouc also has a beautiful central square.

I've just returned from 12 days mostly in Prague, so I'm no expert. However, there's one place in the city that Rick doesn't mention in his guide to CR. It's Vysehrad, which is a big park and cemetery. Dvorak, Mucha and Smetana are buried there. The cemetery's beautiful and interesting, but the park itself is lovely with terrific views of the city that you don't get from Petrin Hill. There are several very nice cafes. We were there in December and really enjoyed it, but I'll bet it's really beautiful in Spring and Summer.

I would give my vote to Cesky Krumlov! It is a jewel of town with its charming cobblestone lanes and riverside views, overlooked by its historical castle. It is small, quaint, and has its share of original & historic architecture as well. In addition, it has great restaurants! I was fortunate to be able spend a few nights there. This allowed for quiet strolls through the town early in the morning and late at night, giving this town a very relaxing ambience.

colcese1, we really enjoyed Vysehrad too!

On our visit to CR. few years ago, we decided to forgo Cesky Krumlov in favor of a couple towns in Moravia- Znojmo and Mikilov. Liked them both a lot, although I'd say we enjoyed Znojmo more for both personal reasons and due to the weather. It rained the while time we were in Mikulov, ruining our plans to cycle to Lednice/Valtice, and we both caught colds in the process. We'd love to go back and explore further- very little English spoken but it was part of the adventure!

We hit Cesky Krumlov when they were having a folk festival....what more could you ask!