I like 18A and 18F on the 737-700, since you have unlimited leg room. However, your seatmates in the center and aisle seats only have normal economy seat pitch. There is no way to leave A or F without them having to get up. You could go in front of row 17, since they do have extended leg room. You would still be disturbing them, but they probably don't have to get up.

On the 737-800, 18A and 18F have extended leg room and your seatmates in the center and aisle do too. You can probably exit without them getting up, but it is unlikely you could do it without disturbing them.

Keep in mind that row 17 does not recline, so it's not good for a long flight. Also, you need to speak Spanish to sit in an exit row seat on CM. See this thread:

http://www.flyertalk.com/forum/other...g-spanish.html