Personal experience is that there are not a lot of coaches attending that are on the lookout to discover a player. If there are coaches that want to see your son play and they are from the area then they may attend to specifically see your son play . In general I don't think there are a lot of coaches just trolling fields to discover players (It does happen sometimes but generally for pitchers who can be isolated the event). If your son is on a team that has a lot of recruits being observed then there are looks from coaches who may be attending to see other players.
Personally I did not think the planners of the schedule had a clue on geography. They routinely schedule teams to play on a high school field then schedule a second game an hour away on a different HS field. In general the field scheduling simply did not make a lot of sense. It was difficult to find a Hotel that was relatively close to all the fields that your team plays at. I put 300 miles on a car in three days at a tournament, the scheduling made no sense! Team played on a Friday at Elon, then two games on a Saturday at spread fields, then game on Sunday evening 100 miles from Elon. Your team will generally play one game on a college field then the remaining three on HS fields. Due to the dispersion of fields it is simply a logistical challenge for coaches to see a lot of players. While playing at the college field there is a decent chance that a coach from that school is attending if for no other reason than to enable access to the field. They often have several college fields, so at say in Western Virginia you may play at JMU, Bridgewater, Eastern Menonite, etc... Maybe one or two fields just depending on how it works out. At JMU you could play on the Varsity Field or the older field used by the club team.
On the plus side I thought the umpires generally were well suited for the environment. Very competent and congenial. Games generally were started on time and little overall controversy.
Games can sometimes be a mismatch that makes for a worthless experience. Our 17U team once played a 15U team in a showcase. It was three inning no-hitter and very embarrassing to win. Yes, the 17U team won. At 16U and up teams with good pitching and defense can generally compete with any team, but even allowing a 15U team in a showcase was very questionable judgement. Strangely, there were several 15U teams in the one showcase so they could have easily scheduled them at a more appropriate peer group.
If this is a high cost trip, with no guarantee of a specific coach seeing your son I would put the money towards a different venue. Dynamic runs an early Summer workout/showcase often near Fredricksburg that is attended by around 60 colleges from Va, Carolinas, and PA. The showcase is one day and cost around $100. It does provide for a great deal of exposure at a very reasonable cost if the schools are a match for your son. If there are schools attending that are of interest I suggest your son contact them so they know he has a interest. Otherwise the coaches have to guess which of the 150 players may want to attend their school. If necessary I'd recommend being bold enough to find the coaches from schools of interest and have the player introduce himself. I assume coaches would at least like to know what players have an interest in their school if they too are interested. This is a relationship which requires mutual interest from both parties.