Scott, changing the goal posts (to use your phrase) is the key I feel. I did the Amsterdam marathon in October (my second marathon) and after starting training rather late did a two week taper after a longest run of 16 miles. I was fine on the day - but realistic about my time and therefore plodded along at a slow speed but really enjoyed myself.
I'm local and may be interested, Lauren, but I'm not sure what you mean by 5.5 for a half marathon. I ran the FLM last year for the first time in 5:08, hoping for somewhere around 4:50 this time.