I live in Wilmington DE (North off I95) Marsh Road Exit all my life 50YO. Commuted to Philly for 25 years.
My daughter rides and has been in most of the barns that have been mentioned in these posts over the last nine years.
Vicmead is a serious Jumper type barn and boarding is over $700.00. If you want to show rated and have a very nice horse this is where you go. Structured, serious, intense training. Nice horses, Centreville DE off Rt52 15mins from the office.
Wellspring: KC manager, Philly Pike eventer/dressage Part of a state park lots of nice trails a huge outdoor. Barn is very run down and spendy for what it offers $500-$600 Board (if they have it available). <5mins from office
Gateway. Kennett Square off old Kennett Road. Nice location -backroads will take 20 mins from office and it is an easy drive. Adjacent trails, outdoor and something they call an indoor but most would not use it. Small metal barn with stables on the inside and outside (25 foot wide). Busy and some very nice instructors and people that work there. Not saying anything about management. No pasture board, but stalls are $550+. The location is what drives the cost not the quality of the place.
I could go up into Unionville/Chadsford but it really starts to get expensive and running out of time. Any further you have to use RT 202 or the blue route and traffic at rush hour is a nightmare. Literally, you can get stuck for two hours.
Check some of the private barns on Craigslist. Some very nice places up there.
Don’t rule out southbound. Traffic and prices just keep getting better in this direction. Going north you are just running into higher and higher demographics $$$$. Try Bohemia Creek Stables in just over the line in MD. Basically it is Middletown. I-95 South to 896 or Route 1 south to Rt 299. You can get there in 35 mins. Amazing huge new indoor, great outdoor, quality care and boarding is very reasonable. Very pretty place with cool people that are as drama free as you will find. If they don’t have a website, try facebook. Eileen is the person to talk to.