Never be afraid to disturb someone sitting on the aisle. It's a risk we take to have our preferred seat. I'd rather have someone else crawling past me, than me having to crawl past someone else. When my bride travels with me, I usually book us both on an aisle seat. Either right across the aisle from each other or in a 2-3-2 configuration I'll book the two aisles in the center section with a good chance no one will book the center seat. If they do, it's my wife's call if she wants to move to the center or let the 'stranger' keep the center seat. But I won't give up my aisle for anyone, including antsy kids with asthma. I'll be polite and accommodating but don't call me rude just because you didn't plan far enough in advance to book seat that were not in the middle of a four or five seat row.