Not sure what a seedy, honky or poky trip is! No one will force you ladies into some sort of bar against your will! Thousands of tourists pass by bars every day and are never bothered by the nightlife in Bangkok or Pattaya! Millions and millions of tourists visit Bangkok every year and have an absolutely wonderful holiday with or without any visits to the nightlife! Don't skip Bangkok, it won't ruin your reputation!
Mention how much per night you want to spend on a hotel so you can get recommendations closer to what your budget is. Start in Bangkok, stay there for a few days. While in Bangkok you can arrange flights or trains to other areas in Thailand. You can get tours through travel agencies in the major cities like Bangkok, Phuket, Chiang Mai and Pattaya.
My advice is to stay in a hotel near the Skytrain route so you can use that overhead rail service to get around the city. If you are young, right out of school then perhaps you may want to stay in the Khao San Road area with some of the other really young travelers. No Skytrain in the KSR area. Finish your holiday in Bangkok again so you can do some last minute souvenir shopping and perhaps take in a dinner cruise if you want. This way you will only be a short meter taxi ride to the airport.
Below travel forums have some good advice on hotels and some things to see. Read up on Thailand first so you can plan your moves. If you want to walk around a bit try the Chiang Mai area. Read up on transportation from the airport and some ideas on where to stay.
http://www.tripadvisor.com/ShowForum-g29…
http://forum.virtualtourist.com/forum-14…
http://www.lonelyplanet.com/thorntree/fo…
Plan on how you can stay in Thailand for 6 weeks. You may need a visa; if you are from UK you only get 30 days free entry at the airport.
Good luck.