Anytime you need a hotel recommendation always mention how much per night you want to spend on a hotel room! Two stars, 3 stars, 4 stars, no stars - some rooms may be around the same price. Even NO STAR hotels have private toilets, TV's, safety boxes, hot water, maid service, etc. Rooms with air and private toilet/shower start around 600 baht.
Asia Hotel. Look for special prices. Right on a Skytrain stop. Easy walk down to Pratunam shopping on Phetchaburi Road. You can use the Skytrain to take you to MBK, Patpong, Chatuchak Weekend Market, Ekamai bus terminal. Meet with the subway for rides to the Hualamphong train station. Also the Skytrain connects to the new Airport Rail Link.
http://www.asiahotel.co.th/asia_bangkok.htm
The Vie Hotel is not far from the Asia Hotel and that Ratchathewi Skytrain stop.
http://www.viehotelbangkok.com/
This hotel is in a different part of town. Near On Nut. Easy walk to Skytrain. The Imm Fusion Hotel:
http://www.agoda.com/asia/thailand/bangkok/imm_fusion_sukhumvit_hotel.html
Skytrain/Rail Link/Subway map:
http://www.urbanrail.net/as/bang/bangkok.htm
For tours visit a local travel agency. Some hotels have tour desks too. Find a tour in the morning and sometimes be on it that same evening. Google up "what to see and do in Bangkok" and you will get several links like this:
http://www.asiatraveltips.com/ThingstodoinBangkok.shtml
You really ought to check out a Frommers or Lonely Planet travel guide and plan your moves to save time and money.
Below travel forums may be helpful for currency, transportation, hotels, scams, safety, etc.
http://www.tripadvisor.com/ShowForum-g293915-i3686-Thailand.html
http://forum.virtualtourist.com/forum-1943-1-Travel-Thailand-1-forum.html
http://www.lonelyplanet.com/thorntree/forum.jspa?forumID=51
Good luck.