Khon Kaen is a good mix of old and new. You can get KFC and Pizza or you can eat noodles and rice from street vendors. Software and DVDs are available at the mall or you can shop at the open markets. Small guest houses, intermediate hotels and a 5-star accommodation are available.
Nightlife can be found-- but don't expect it be comparable to Pattaya or Bangkok. There are a few expat bars near the Sofitel Hotel and a few Thai clubs scattered throughout the city.
Transportation around the city is easy as the Baht Buses are color-coded. Baht buses are just pick-up truck with seats in the back and cost about 25 cents for a ride. The have set routes and maps are available that display the routes. You just need to figure out where you want to go and find the correct color and hop on.
Day time activities for me were shopping and sightseeing. I spent lots of time visiting some of the most beautiful temples in all of Asia. One in particular is located in the heart of the city; right along side the city's lake (Buun Kaen Nakorn). The temple (Wat Nong Wang Muang) is 9 stories tall and each floor has a mini-museum with artifacts from ancient Thailand. Music classes were going on and one of the Buddhist monks gave us a blessing.
I visited other temples in and around Khon Kaen and one was about 1000 stairs to the top to see a beautiful, pure white Buddha called Pu Don Fai. It was a hike, but definitely worth the walk.
For lovers of Thai food, there is an abundance of restaurants throughout the city. Many of the restaurants are around Lake Buun with excellent Thai and Western food at very reasonable prices. A typical night out with 3 or 4 dishes, a couple of Singha beers and the total tab would be about $12. Delicious food in open air restaurants with a view of the lake or one of the rivers in the city made for some very relaxing evenings.
I spent one day fishing at a small lake. Bait, tackle and a comfortable chair cost all of 200 Baht (about 6 dollars) for the day. There was also a restaurant that served up some good food and cold beer. I didn't catch any fish, but had a very relaxing day. I also went out to King Cobra village to see the snake show. A good show with no admission fee. Sat in the bleachers and watched the 1/2 hour show and gave 100 Baht when they passed the hat.
All in all, a very relaxing 3 1/2 week vacation and I look forward to my return trip next year.