Hi Tony, and welcome to the wonderful world of HA!
I have been using SmartThings for about 4 months now and love it!! I have about 40 devices so far and this number is growing weekly. I have learned a lot from these forums and when I get stuck I have always found answers here (good or bad) . My advice is to start with a couple rooms at a time and then expand from there. The addiction will take over and guide your way to the next level.
I have been one of the lucky users who have not struggled with a lot of the issues you might come across on the forums. I like to think it is because I am not a programmer or in the IT field and and keep things as simple as possible. I am also not using a ton of custom device types, or Apps. I am just now starting to play with some like Alexa Helper, Big Talker, LANNouncer and Smart Tiles. However, the more custom stuff I use the more concerns I have about stability.
Anyway, I suggest you subscribe to the Best Deals Thread here to understand what a good deal really is: (Pre-Subcategory creation) Deals/Sales/Coupons/Pricing.
The wiring on my house is not conducive to HA switches so I was forced to use individual bulbs everywhere. It works out to be about the same price if you can get a good deal on bulbs. Overall I am very satisfied with the results,
You are definitely going to want some door sensors. You can’t control a lock very well if you can’t confirm a door is open or closed. They are also great for home security, turning on lights, or just to know when people come and go from my house.
You will probably also want some motion sensors. They are great to automate lights and for security monitoring. I haven’t touched several of my light switches in months!
In regards to Locks, I have 2 Quickset and one Yale lock. They both work equally well for my needs. I live in North Dakota and the batteries do take a beating but I have yet to replace any and it has been 18 below zero several times this winter.
I have not done any automation with my entertainment center yet, but it is very high on my priority list. It sucks having to find my remote to turn off the TV when I can turn off the rest of the house so easily using Alexa. I just need to justify the high price tag on the Harmony System first. From my research the Harmony system will do pretty much anything a person could need with a wide variety of products, and integrated well with Smartthings
I am in the process of automating my garage doors now. I am pretty sure I an going with the GoControl/Linear system, but still researching and looking for more feedback on that still. It definitely is not something I want to jump into due to the high cost. My door sensors already provide great feedback, but being able to close them remotely is something I just gotta have for sure!
I also have 1 camera from the compatible list installed and I am not impressed. I was expecting to have much more control and better integration with things like motion and sound sensing. If I could do any programming or Samsung does a better job supporting these I suspect this will eventually be a reality. It also appears that integration with Smart Home Monitor is going the pay to play route and this is very disheartening.
Sorry this reply is so long but I hope you find some value in it. Be prepared to let your geek play (and your wallet) and have some fun!!