Bangkok sight-seeing

A couple of friends of mine are coming from the U.S. for a business trip to Bangkok. They have done the Palace and the Wats on an earlier trip. Looking for suggestions for somthing else for a day-trip. Someone has mentioned
Sampran Elephant Grounds and Zoo to them. I have never been there.

Muang Boran or Ancient City, it's a park outside town in Samut Prakan with copies of Thai buildings from all over the country. You could rent a taxi for the day and use the taxi to visit the place.
I advice against walking, you will understand why once you get there. Seems you can hire bicycle now.
Entry price 350 baht pp.

I avoid places like crocodile farm and Rose Garden, but Ancient City gets 5* from me.

see their website ancientcity.com

- Vimanmek Teak Palace. Over near Dusit Zoo, this was Rama 5's palace. On the grounds are the Royal photography collection in several houses as well as the garages with a collection of antique cars and coaches
http://www.bangkoksite.com/Vimanmek/index.htm

- Dusit Zoo.. a good walkabout, perhaps 2-3 hours max.http://www.bangkoksite.com/Places%20to%20see/DusitZoo.htm

- Temple of the Golden Mount (Phu Kao Thong) on a man made hill in central Bangkok. Very interesting temple with historical paintings behind the hill.. A goodly hike up the hill with a decent view from the top of the temple.
http://www.bangkok.com/attraction-temple/wat-saket.html

- Baiyoke II Tower- Tallest building in Bangkok. Revolving deck on the top and right below the top a buffet restaurant.
[url]http://www.virtualtourist.com/travel/Asia/Thailand/Central_Eastern_Thailand/Bangkok-1445238/Things_To_Do-Bangkok-Baiyoke_Tower-BR-1.html[url]

- Ayuttaya ancient capital. About an hour north of Bangkok, easy access via expressway.. This is a 1/2 day trip minimum and best bet is to rent your own tour van (Lot Doo). Mahy temples and ruins to see. http://thailand.tourism-asia.net/ayutthaya-historical-park.html

- Bang-pa-in (Royal Summer palace) about 30km south of Ayuttaya on the Chao Phya river. This would be a nice follow-on to Ayuttaya, hitting it on the way back to Bangkok. http://www.bangkoksite.com/folder109/BangPaIn1.htm

-Bang Sai Royal Crafts center: This Royally sponsored project provides a teaching and market venue for Thai crafts. The center has shops you can walk through and watch young Thais learning the craft as well as a large building selling items. Colocated on the center is a large fresh water aquarium and a collection of traditionally built Thai houses representing all regions of Thailand.. Thai dancing, faux marriage ceremonies and other cultural displays take place in this village. Bang Sai is 24KM south of Bang Pa In on the Chao Phya river. http://www.thailand.com/travel/recreation/recreation_ayutthaya_bangsai.htm

- Safari World: located NE of Bangkok in Min Buri, less than an hours drive from central Bangkok. Large outdoor Safari park and multiple venues with park "shows" Go on a weekday that is NOT a Thai holiday and you'll find it crowdless.. http://www.discoverythailand.com/bangkok_safari_world.asp

- Jim thompson house: Traditional Thai teakwood house built by renowned and disappeared entrenpenuer Jim Thompson. located near MBK and the mall strip near Siam Square: http://www.jimthompsonhouse.org/

- chao Phya dinner cruise: there's a million of em'.. I would NOT go on any of the big ones that are packed full of foreigners. You could try Yok Yor Marina cruise which has a nice Thai dancing and fighting exhibition prior to boarding http://www.yokyor.co.th/english/yokyor/promotion-boontarika.html or what Parrot took my wife and I on about 5 weeks back, the Dairy Queen Seafood Restaurant http://www.asiatraveltips.com/RestaurantsinThailand.shtml which has a converted rice barge that was not crowded at all and a long cruise.. Downside is it's way on the northside of Bangkok

I've done all these places more than once, and that's a plus..

Thanks a lot.
Not only a good list for my visiting friends to choose from, but it is also a good list for us.