It's important to note that this meeting is very unlikely to have been one of equals, like something along the lines of the G7. King Edgar is known as 'the Peaceful', not because no fighting occured during his reign, but because according to the Anglo-Saxon Chronicle, no invaders or raiders on England were successful in attacking during his reign. He was politically and militarily very powerful, and the other kings were Welsh, Scottish and possibly Hiberno-Norse sub-kings that he would have summoned to meet him.

Chester was one of the leading cities of Anglo-Saxon England, and for much of the tenth century had rivalled London in terms of economic output. Unlike many towns, it still had its Roman walls, which had been restored by Æthelflæd in 907. Chester is just south of Liverpool, which should tell you that it's in a fantastic position for maritime trade with the ships of the period, and it was a crossroads of sea trade from Ireland and the Scottish Isles, and land-based trade along the old Roman road network as far as London.

It would have been an impressive city to visit, one the other kings were possibly familiar with, and likely outstripped anything the other kings would have called home. Not only does its location make it very convenient for the other kings and Edgar to reach, but it would have been a show of strength to illustrate that this was not even the capital of England.

The other kings would have arrived by sea and possibly brought small fleets with them. Edgar would likely have had his household soldiers with him, but probably also the local fyrd, a semi-professional militia and the closest thing to a standing army, may have also been called into service for additional security. It's probable that the other kings would have been accomodated by Edgar as a display of hospitality. This could have been at the Abbey of St Werburgh, or in a royal manse nearby.