We got a system when we built back in 94 that can be monitored, but we never have. We got a package with smoke alarm and motion detector inside the house, the basement has a heat rate of rise detector. We also had all doors and windows set with detector that break when opened. We park in our basement so installed a control pnael there. Another on the top floor, master bedroom so we can set it before going to bed. The system has a couple of modes, one is Away mode, everything is fully armed. The other mode is stay, all perimeter alrams are hot, but the inside motion detector is turned off. We have a dog inside so that is very handy. mine is also expandable although not wirelessly to include an outside building.
Bottom line, think thru what you feel you need, then talk to 2-3 different companies and see what they can offer. We went with one of the off brand co's. Got exactly what we wanted at what we felt was a good price.