I am considering adding a cooling fan near the nozzle.
Tin

so if you try PLA on one of the older models be extreamly careful during change out with temps and keep plastic flowing so it dont sit long in hot head when over PLA temps.

also you need to create a new filament setting in Slic3r for PLA with its temps etc and be sure the correct setting is used in slicer tab for filament in use even after going back to ABS

This statement can be misleading as new users tend to misunderstand the possibilities of their new printer. Many people prefer PLA due to the smell or for environmental reasons. It is more than possible to print PLA on a stock Solidoodle, and this thread is intended to be a "one stop shop" to cut down on the increasing number of threads asking this very question.
This has also been discussed Here

PLA (Polylactic Acid) is made from corn, sugarcane, starch, and so on. This gives PLA not only a more environmentally friendly characteristic, but also smells much better as extruding ABS smells like...well...burning plastic, whereas PLA smells like maple syrup.
A great link giving the differences between PLA and ABS and be foung Here
When talking about printing PLA, especially on Soliforum, you first want to take the hotend into account. The stock Solidoodle hotend is very capable of printing PLA, but many users on Soliforum have upgraded to an E3D all metal hotend . One of the many differences between the E3D and the stock SD hotend are where the thermistors are placed. The thermistor used on the E3D is more accurate not only because of the type used, but also where the thermistor is placed. This will give a range of 30c +/- difference in your conversation. So while the E3D would extrude PLA at 210c, the stock hotend would be set around 180c. Bare this in mind when looking up settings from other users.

Problems With PLA
PLA is more notorious to clog your hotend. Be sure you extrude at a lower temperature rather than higher. If it is set to extrude at 245c, this setting is too high, the filament will melt before reaching the nozzle, and will cause a clog. As with any filament, do not attempt to extrude UNDER the recommended temperature, or you could strip the filament or potentially damage your extruder.

PLA takes longer to cool than ABS. This may not seem that big of a deal, but it certainly can be. If printing a small part, the hotend will be close to the part for long periods of time. This would mean the part has not been given enough time to properly cool down before the next layer is applied. This is easily combated by installing a fan onto your hotend to actively cool the filament as is is extruded. Whether using a 30mm fan or 40mm fan, and whatever extruder body you have, there are many designs for mounting found Here
If you do not have an enclosure on your printer, you can easily use a desk fan.

Because of its low melting temperature, it is not recommended to print some items like a new extruder out of PLA since many users have mentioned their extruder bodies were melting mid-print. This is not a good position to be in when meeting a deadline.

Is PLA right for you?
When properly printed, PLA can be tough as nails, but it all depends on what application the print is being used for. As with any material, you need the right tool for the job. PLA has been reported to break down in water much faster than ABS, and claims have been made that the printed part will melt if left inside a hot car on a summer afternoon.

Finishing/Smoothing PLA
Unlike ABS, acetone has virtually no effect on PLA. LdyMox posted here results experimenting with MEK Here

As proof you can indeed print PLA on a stock Solidoodle, I printed a massive geared heart before I made any real changes to my printer.

Hope this clears some misconceptions, and happy printing!