I am from that area Wes. I can remember when I was taken there several times as a kid. There used to be wooden steps all the way to the top. There was no vernicular, no Park Rangers, and a Steam Engine was on display at the top.
There was a small stand at the bottom where you could get an ice cream cone, and across the street from that was an old wooden PRR Caboose on display.
The PRR regarded the curve as the Engineering marvel the East end of the Pittsburg Division was. Passenger Hawgs were required to notify the Conductor when they approached the curve, and the Conductor made the announcement in each car that they were approaching the World Famous Horseshoe Curve and which side of the car to look out. PRR kept the trees cut to where you could see all the way around.
There is a famous after dark picture that was taken by Sylvania? photographic flash bulb company, with the cooperation of PRR. I wish I had a copy of the framed picture of it that hung in many a PRR mans home. (altho I have many relatives who have one, mine went to my dads sisters side of the family)
Then came PC and then Conrail. No money to cut the trees, or fix the steps. Somebody set fire to the caboose and burnt to the ground. Then the city of Altoona decided that it could spur tourism. With the decline of Mining, Steel, and Railroading, the area needed something more than Golf Courses and Nursing Homes. They went up on the curve and took the Steam engine. Then they spent a couple bucks on it, then ran the piss outta it. It has some major defects that have to be fixed before it can run again, and since there was no one with the knowledge or tools to work on it, they sent it to Scranton, PA where it has rested in pieces for many years now. They put a GP-9 in its place up on the curve.
They built the Railroaders Memorial museam on the site of the Master Mechanics building in Altoona. They completely rebuilt the building and put displays up. Thats where you should have went first. As they were doing this the Park Service decided it would be good to completely redo the curve. They built several buildings, a big parking lot, new concrete steps, and a vernicular (inclined plane railroad) to the top to provide access for Disabled People. Thats when it was no longer free to go to the top. You have to pay just to walk up. 
Then NS came into the picture. Then the flashbulb company wanted to redo the picture it took 100 years before.
So the park service and NS got together and cut the trees.
They took a picture, which was by no means anything like a picture event. It was more like a laser light show, and video would be better to see it than a picture.
Then NS closed the Hollidaysburg Car Shops that didn't generate much good will, and ended up costing NS a lotta money to clean up. So the trees went on doing what they do best and grew up obscuring the tracks again. Will NS spend good profit money to cut thousands of trees so the park service can make money taking people to watch Choo-Choos??
NOPE!!
Used to be you could walk up for free, at any time. Now ya gotta pay. Now it has hours, and if you go at the wrong time it may be closed, and the guard will ask you to leave. Its just another example of how people think they can lure people in and sucker them out of thier tourist dollar.
If you would have driven up to TunnelHill, (Gallitzin) the top of the mountain, you could have seen the only N5C caboose to be painted PRR without Keystones, AND be equipped with a screen door!!
As far as bang for the buck, paying to tour the Master Mechanics building is where its at in Altoona. 
I used to reccomend people to ride the Pennsylvanian from Altoona to Johnstown, then wait a little and ride the Eastbound Pennsylvanian back from Johnstown to Altoona. You could ride around the curve twice..(more chance to see it not blocked by another train).
You can still do this, but on a Sunday you start in Johnstown around 2Pm and ride to Altoona, stay about an hour, then ride back from Altoona to Johnstown getting back around 6pm. During the week the Eastbound runs early and you leave Johnstown around 9AM so you get about 7 hours in Altoona between trains.
Dont get me wrong The curve is the place ta go ta see trains. Especially if you have kids, they love the screaming dynamics, full out Notch 8, and the squealing of the flanges around the 35mph curve. All amplified by the cut in the face of the mountain that makes the curve a natural ampitheatre.
Its even better after dark...But Oh Thats right, Its closed after dark...
Ya shoulda said something before hand Wes...Specially if ya had kids along, that Pennsylvanian ride is a rare thing. Not too many places you can ride out and back in just a coupls hrs time...altho on Sunday if the first train is late....