Here in Central PA it has been in the mid 70's lately and at night, the temperatures have been about 58 degrees at night. 

 

Any suggestions on what to throw during these situations at night? 

I've been doing some night fishing here in SE KS the past month or so. We had a cold front come through that has dropped the temps down to the mid 60s low 70s and gets down into the 50s at night. I have been doing well with a 3/8oz. Revenge swim jig in Chart/White with Zoom Swimmin Fluke in pearl as the trailer. Slow retrieve around grass lines is what I have been most successful with. Another is an all black Siebert jig with a Havoc Pit Chunk in perfection as the trailer.

for smallies on a river or largemouth in a lake?

Smalies on the river! 

Any other help fellas?

I wouldnt fish nights when the weathers cool..

Night + Cold front, I'd look more towards Jigs, big curly tail worms.. Works well for largemouth, haven't done much River Smallie fishing so can't help ya out specifically. 

Slow rolling a single Colorado bladed spinnerbait is one of my favorite night time smallie baits. I've caught bass at night with snow on the ground and part of the lake iced over, they still have to eat!