I concur. My favourite places are Koksijde Bad and Nieuwpoort. Neither appear cheap and nasty, like many UK seaside resorts can be, and the Kust Tram us a real bonus, as is the pedestrianised promenade.
No mileage in flights from UK from any further south than Birmingham or East Midlands - even from these areas driving to the Belgian coast via Eurotunnel isn't that far, and once you've left the UK, largely stressless.