Back in the 90’s, a company I worked for sent me for a week of training in Boston. The hotel at the conference site was ludicrously expensive, so I managed to find another hotel down the road and convince my boss to go for that hotel and a rental car with unlimited milage for the week and several extra days (that I took as PTO). I then spent those PTO days driving down to New Jersey to visit some people I knew from PBM games (Play By Mail - pre-internet multi-player gaming, baby!) and driving around NY and Mass.
Company still came out ahead over what the conference hotel cost.