In an overwhelming majority of hires outcalls are more expensive than in calls because it takes time for an escort to go to a client's place whether is right next door or miles away, walking distance or by car, uber, etc.
Chasing conventions, games, special events, is very likely to backfire.... prices are waaaay more expensive and how likely is that someone who happens to be visiting will hire an escort considering he's very likely to be hanging out with friends, etc. Besides most locals because of traffic, etc. might stay home.
An escort can always go to Boston.... why going there during the Boston Marathon? Go there the weekend before or after.