I always go to my dr appointments during my working day (9am-5pm) and I go in whatever I wore to work. I got really great "maternity" panties... I find it's hard to like typical maternity clothes as they all have that tie in the back that screams "I'm too fat for normal clothes" HAHA so I went to Lane Bryant for tops and Motherhood for bottoms (they have some great stretching pants for work/play that look like regular pants but have a comfortable elastic waist). I'm not a big girl, US size 9 average in jeans, and I have a larger than normal chest 36F non-prego, so I have a hard time finding clothes... plus I'm highly interested in fashion... it's been hard to be satisfied with clothes being pregnant. Lane Bryant is still really big on me, but I sew so I have altered the clothes to make them fit my personal shape better.
Hope that helps, I just pull my pants down to the pubic bone for scans(none of them seem to have buttons anymore). Old Navy has some really great bottoms for maternity as well...