Assuming 1) a trip is about 10,000 miles in distance, 2) acceleration is constant and speeding up for 15 minutes and slowing down for 15 minutes, they are looki

Assuming 1) a trip is about 10,000 miles in distance, 2) acceleration is constant and speeding up for 15 minutes and slowing down for 15 minutes, they are looking at (very roughly) 0.4g of additional acceleration i.e. you would feel 1.4 times as heavy as you do standing still on takeoff and landing. As you angled horizontally, the effect of earth's gravity would be counteracted by your centripetal acceleration so that you would feel approximately 0.4g at the midpoint of the flight. So 1.4g at takeoff and landing, 0.4g at the midpoint (again assuming constant acceleration due to thrust) That sounds not too bad. Two 15 minute burns sounds in the realm of possibility. Edit: changed some numbers and my conclusion.