I just wanted to chime in to say - don't be afraid to try the Sympto-Thermal method simply because of the sleeping/temperature issue. I know this scares a lot of women off because it sounds so difficult to achieve, but I assure you, it's not!
I've used the Sympto-Thermal method for all 9+ years of our marriage - spacing out our children... and yes, I've been up a lot at night, breastfeeding, kids in bed with me, etc, etc... but that has never affected my ability to get a good temperature sign.
First off... the temperature sign is SECONDARY to the PRIMARY signs of tracking the cervical mucous and cervical position... so if you don't get all the information you need from that temperature sign, you can still make the ST-method work without it.
My advice on temperature taking... set your alarm for a reasonable time every single day (even if you plan on sleeping in - you can take your temperature and go back to sleep without getting out of bed). Also, if you happen to take it at a different time, just make a mark on your chart (I write in the actual time right above the dot on the temp scale)... and even then, you usually have a 60-min window in which you can still say your temperature is "accurate enough". Another hint that many find helpful is to take your temperature vaginally. I know, sounds gross, but if you happen to randomly sleep with your mouth open (congested or something??) you can get "cold spots" in your mouth that can make your temperature readings a little hard to interpret. Taking your temperature vaginally eliminates that because you're "closed off" down there... it really helped clear things up for me personally.
ANYWAY... not to ramble on... I personally really like the sympto-thermal method because it gives me those 2 other signs (cervical position - which is my easiest sign to interpret, personally... and the temperature sign)... and that gives me that extra "peace of mind" that my cycle is indeed doing what I think it is...
Hope that helps! :)