Not a SWA frequent flyer, but I do check the SWA web site at least once per day. It looks like the internet rate has dropped to $59 for a lot of dates up until Nov. 20 BUF-MCO. Hopefully as the dates you are looking for get closer the $145 internet rate will drop down. IMHO, thats the time to book. I would not be surprised if the Dec internet rate went to $59 by the end of Oct. and that the Jan internet rate went to $59 by the end of Nov. Of course, peak travel times will be excluded from the $59. You can tell what is considered peak by going to the southwest web site and looking at their shortcuts calendar. If only very high fares are available for a period of days (ex. right now around Christmas time), that would be considered peak.
Also, check the SWA web site every Tuesday morning. Each week a destination goes on sale and the flights for that city are a great price then. For example, on Tuesday Aug 1, MCO went on sale for $59 for departures until the end of the schd. as THAT time (Dec 10, I believe).
As well, on Tuesday sometimes entire part of the US go on sale (ex. Florida sale). At that time all destinations in Florida go on sale (but not always every date/flight, and high demand flights/dates are excluded). These type of sales are usually set up for set booking windows (ex. a 6 week period).
I like the Tuesday sales because they last a few days, unlike DING which is only for a certain amount of hours. I would prefer to get some nice $59 non-stop flights and then I wouldn't have to be concerned about watching DINGS closely.
I watched BUF-MCO Dec 31, 2005 VERY closely as well as BUF-TPA Dec 28 last year and when Dec/Jan went on sale or DINGed these dates/destinations never dropped in price.
If you can, be flexible with your dates and even with what airports you are willing to fly into/out of.
Again, not a SWA expert, just my thoughts.
Perhaps a SWA frequent flyer would be abe to share their thoughts about SWA sales?