LOTS of food. No hanging around, especially if you're unable to sit down. No travel between wedding and reception. Provide something to do if there is any waiting - outdoor games went down very well at several I've been to, like croquet. I love a ceildih.
I highly recommend focusing on quantity of food, not fanciness (once a basic level has been achieved). I went to a wedding where there was a catered BBQ - burgers, hot dogs, all the sides, loads of veg too. Brilliant! Also, if you're having a sit down catered meal, instruct the caterers to bring out all the "special" plates (allergies etc) FIRST and then the normal meals. Stops people with dietary requirements having to fend off/enquire about dubious plates of food repeatedly while wondering if they've been forgotten about.
Also, consider the volume of any amplification you use. Avoid music so loud you can't hear yourself think on the next room, and speeches so quiet everyone's wondering if they've started.
Speaking of speeches... If someone doesn't do any public speaking in their daily life, they're unlikely to suddenly knock it out of the park at the wedding. Mumblers and drivellers can keep it short and factual. Get your DH to give the best man some guidelines. I went to one where the entire best man's speech was about how everyone assumed the groom was gay until he proposed to the bride, and thank fuck he turned out not to be a poofter, right lads? It was excruciating on so many levels.