The Tulane MakerSpace uses Ultimaker 2 and Lulzbot TAZ-5 3d printers with a heated bed to allow for both ABS and PLA printer filament. ABS filament allows for better finishing effects (such as smoothing), but PLA provides a more rigid part and has has much better adherence to the print bed. There are other advantages and disadvantages to both. Cost is the same (currently ~$18 per kg).
The standard slicing software favored for these printers is Cura, which allows you to arrange and size your model and set options for the printer to follow. Use the Lulzbot version of Cura for both machines https://www.lulzbot.com/cura
Recommended settings - Dual Extruder Taz
PLA: 9/28/2015 settings of .... with 3mm PLA and 3mm PVA worked well
Recommended settings - Single Extruder Taz
Recommended settings - Ultimaker 2
ABS: because of contraction due to cooling, ABS tends to lift away from the glass build plate. This is worse for square corners; round objects rarely lift. In Cura, specify a raft around your object. This way, the raft will (possibly) lift but your object may stay flat. When the build-plate is still cool, paint a thin layer of ABS paint (glass jar) onto the clean glass build plate. The dried ABS paint will further anchor your object to the build plate. Recommended settings are ......