I know the area of Pennsylvania you are from very well. I grew up 20 miles southwest of Hazleton and fished many of the streams in central PA that you have either fished or will fish. Since there is such very good trout fishing (especially Penn's Creek, which is parctically in your backyard) and smallmouth bass fishing (the Susquahanna and its two branches are terrific smallmouth fisheries, which are in your front yard), I recommend you look at a 6 wt rod of between 9'-10' long. Personally, I'd get a 10' 6 wt because the Susquahanna is huge water and lower Penn's Creek is not exactly small either.
The 10' 6 wt would allow you to fish for trout in all but small streams and it would have the length for better line control needed on large water like the Susquahanna. The 10' rod is not too much for even creeks the size of Deer Creek. A 6 wt is a far better choice for fishing for smallmouth and trout with streamers than a 5 wt because is better suited to casting them than a 5 wt.
The 6 wt is not overly large, in fact up until about 12 or so years ago, it was considered the best all-around choice for trout or smallmouth. A 6 wt can also easily handle pickerel, another fairly abundant fish in the Susquahanna and some of the other rivers near Lewistown. Another plus for the 6 wt, it can handle mid-sized bass bugs for the largemouth bass available in the Lewistown area.
If you decide you wish to fish for stripers or to try for nothern pike or the monstrous muskies found in the Susquahanna, you will need to get a second rod of 8 wt. or even better 9 wt. That second rod can wait for a later time though.
There are quite a few good 9'-10' 6 wt rods on the market these days with prices under $300.00. In fact, there aqre some very nice casting rods of this size selling for under $200.00.
The best way to get some decent equipment with the proper line and a decent reel is by visiting a local fly shop. There used to be a very good shop in Lewistown; however, I don't know if it is still there because I left Pennsylvania nearly 26 years ago and live in Washington state now. At any rate, you live in a part of the country with a long-standing fly fishing tradition that has a plethora of quality fly shops scattered around all parts of the state. E. Hille up the road in Williamsport or the several shops down the road in Carlisle would be able to help you tremendously.
The shop owner or employees will help you get decent equipment and will also help you get started with fly casting if you get the rod, etc. from them. And since they will want repeat business from you, they will treat you fairly and provide far more service than any large mail order house like Cabella's or buying from Ebay will ever make up. My point is the local shop will be able to do things for you to get started correctly that cannot be matched.