So Good They Named It Hull (Solution)
by Katie Steckles and Paul Taylor with clues by John Wiesemann
The entire trip is planned relative to Chester and Glastonbury. Locate both these places in both England and New England, and this fixes the position of one map relative to the other. A solver would proceed by locating all of the other named places on the map of one and marking them on the map of the other, relative to Chester=Chester and Glastonbury=Glastonbury.
'Staying overnight' in the text corresponds to drawing a line between the locations of that place on the England and New England overlaid maps. Travelling from one place to the other, using a mode of transport specific to either England or New England, corresponds to joining those two (different) towns on the appropriate map only.
For example, 'staying overnight in Grantham' means a line between Grantham, England and Grantham, USA. Travelling by Greyhound Bus from Warwick to Gloucester means a line between Warwick USA and Gloucester USA. Travelling by National Express coach from St Albans to Chelmsford means a line between St Albans, England and Chelmsford, England.
Each paragraph gives an arrangement of lines which makes a letter of the alphabet. Screen grabs of each are shown below. The letters spell out VARIABLES, which is the answer.