I know nothing about the Sony HX90V, but I think it is a good one for Jenn. For two reasons.
Don't know why Jenn wants a viewfinder, and few point and shoots have this feature. I for one will not buy a camera without a viewfinder. Part of it is out of habit from film camera days, and part is for stability (more to follow).
Without raw, Jenn won't be tempted to go down that path, at this stage. With raw, files are much bigger, shots are slower, native sw that comes with the camera for raw conversion is typically not the best, better raw conversion sw can be expensive. The learning curve will be steep and post processing time can be lengthy, 500 page books are written on the subject. But the real kicker is that 99.99% of the shots for Jenn's purpose don't need it.
The RX100 is an excellent camera. If its zoom range is better, say to 200mm, I would own one. I'm hopeful that there will be one in the future. If Jenn should compare the Sony HX90V vs the RX100 in a store, try the longest zoom on the RX100 first, followed by longer zooms out to 200mm on the HX90V. That range would cover the majority of shots she will encounter. Then she can appreciate the difference, and decide if it is significant or not
Once Jenn has her camera in hand, and after reading the manual (she will do that, won't she?), the first thing to learn is how to hold it correctly for sharp photos. Here's a good simple intro about the upper body. Search the net for tips on lower body stance, and on breathing. Holding a camera with a viewfinder against the head adds stability. Without these techniques, holding phone/camera with stretched out arms will not result in consistently sharp photos. Many who don't hold their cameras correctly will blame their equipment for blurry photos.