Santiago Travel Forum

We expect to take an overnight bus Santiago to Buenos Aires - probably TurBus - probably Premium service. I'm wondering if, similar to an airline, you can bring a small suitcase on board with dimensions up to 23 cm x 40 cm x 55 cm ? That's what I'll have on the plane to Santiago for things I want with me and I wonder if I'll have to repack for the bus?

Don't know about these buses, but those in Colombia and Peru. Mind that the buses won't have overhead bins like in airplanes.
This may become uncomfortable and maybe dangerous as the "hand-luggage" can fall out of the overhead "hat-rack" especially in mountaineous country.

Firstly, Turbus doesn't go to Buenos Aires. It only goes to Mendoza. The best company doing the Mendoza to BA route would be this one:
http://www.vytsendas.com.ar/
http://www.vytsendas.com.ar/servicios.html
http://www.vytsendas.com.ar/index.html
Salon Suite is their top service. Their website isn't the best, but there is a fax contact at the bottom of the page.
Andesmar is another good company. The buses to BA from Santiago all go through Mendoza, I think. Often you will change bus in Mendoza. The whole journey takes about 20 hours.
As for luggage, yes you can store a suitcase underneath the bus, or even more usually. You will get a numbered receipt for it. As long as it fits in the overhead rack above you, you can take whatever you want onto the bus. Anything an airline allows is usually fine.
Tip: Keep anything of value beside you on the seat (iPod, laptop, phone, money and documents). Bus stations have always been tricky places, but occasionally a thief thinks it is worthwhile to buy an expensive bus ticket as the passengers probably have goodies to steal.

If you do use the overhead rack, place your stuff in the rack across from your seat so you can monitor it. In general, your stuff (in Chile and Argentina premium busses) is safer below the bus. Of course, all real and personal valuables should be on or attatched to your person at all times.

NOTE: someone on Thorn Tree just started a topic on luggage theft on Andesmar.

Thanks to everyone for very helpful and useful replies.