Smart phones all have built in GPS's so coordinate viewing is simple. The GPS app looks just like any other GPS. Many of the apps also allow you to download maps so that you can view your maps even when you are outside the cell network. I have several apps on my iPhone that have downloadable mapping and they work very well (exactly like a handheld GPS, with coordinate display, tracks and waypoints).
The only disadvantages with using the smart phone is battery life and fragility. Battery life is not an issue as long as you are going to use it as you mentioned, just grabbing coordinates once in a while and not leaving the smart phone GPS on all the time. I used to put mine in a small dry bag however, I have recently bought a waterproof case that allows me to use my iPhone in wet conditions (nice since I'm a fisherman).
The Spot Connect (or Spot 2) will drop a track point down every 10 minutes and the points are uploaded to your own personal web map (hosted by Spot), so your friends and family can follow your progress. The smart phone doesn't have to be left on once you turn on the tracking, it is only needed to turn the tracking feature on initially or to send an "I'm OK" alert.
The predefined messages on the Spot Connect are really a plus and I've used one of those already... "I'm going to be late" comes in really handy when the fishing is good!
Edit to add: I should have mentioned that your messages can be sent via email, Twitter or Facebook as well as going to the web map. You can set up various contact groups on your smart phone (and on Spot's site) and select whichever one you want when you send your message. Adds a fair bit of freedom to your messaging.