The 120VAC levels are going to present a problem depending on which device you choose.
Space can be a problem depending on which device you choose.
I have used these:
http://www.bb-elec.com/Products/Wir...ss-Modems-and-I-O/Zlinx-I-O-Base-Modules.aspx
The pros are reasonable cost and compact size.
The cons are that you have to buy a programming module to set them up and they are not the most well built devices. For one of mine, I had to attach the programmer module and twist it and hold it my hand "in a bind" to keep connectivity long enough to get it configured. Once I got it installed it seems to work just fine. My situation was for analog I/O which required some non-standard configuration. You might be able to buy the pair of devices pre-programmed so you don't need to purchase that separate device.
DataLinc group makes a pretty good product. It has some pros and cons as they all do. I have used their PlantLinc hardware in some cases where the poor electrical conditions combined with the fact that all the I/O on the remote devices have commons internally tied to each other and ground rendering them unreliable. Their setup software does not play well with OS newer than WindowsXP in my experience as well. The are built in a nice rugged but bulky housing with lots of handy indicator LEDs. You'd need interposing relays to be able to use them with 120vac signals.
The best radio I/O devices I have used are Phoenix Contact TWE (trusted wireless ethernet):
https://www.phoenixcontact.com/onli...26-02-03/becca8d6-0b50-494a-8646-9c868263e4d0
They are not cheap but they hold up well in hostile temperatures and horrible electrical sites. They do have RS-232 and RS-485 ports so you don't have to use the Ethernet. The I/O can be added on in a modular fashion. Many of my sites are at the end of electrical transmission lines and controlling big water well pumps which generate bad surges and sometime ground current noise. The TWE has not suffered in these conditions so far. Setting them up for my applications took a little bit of head scratching since I was talking Modbus to them and not just doing simple point to point I/O replication. Once I figured out what their terms meant in my world, it was easy. All of the setup is done with a browser.
Phoenix also makes a Radioline which I have not used yet, but might be right up your alley. It looks a lot like the B&B stuff, but probably costs more and might be worth the money if it is better built. Love their products...website not so much:
https://www.phoenixcontact.com/onli...26-03-05/003d60ad-835c-4299-ab30-c4480f52914d