I got the Echo Dot (2nd gen) last week and I love the thing. More importantly, my wife does as well. We are already planning on getting 2 more in the near future.
I want to take small steps with the lighting as to not break the bank. That and just a year ago, I replaced all of our bulbs with Cree LEDs at $5 each. So I like the bulbs I have and have no real desire to replace them, but I may have to in order to get what we are looking for.
I want an option that is dimmable, maybe do color change in the future and works with voice control via Alexa (obviously).
I put in 1 TP-Link smart plug that I use to control the on/off of our main lighting in our living room. Obviously I cannot do any dimming with this. I am torn as to which way to go next. I like the $70 Philips Hue standard hub with 2 bulbs. Can that standard hub control color bulbs if I buy a few down the road?
Yes, the current hub (though Phillips' uses the term "bridge" for their product) will work all types of Hue bulbs (as well as the one motion sensor they sell).
Additional bulbs being $15 is nice as well.
I assume you already know this, but just to be safe...the $15 price only applies to the white A19 bulbs. The multi-color bulbs are significantly more expensive.
The Smartthings hub is an option as well but I do not see us adding much in the way of smart items beyond maybe a door lock. That would be down the road, and I bet designs would include optimization for Alexa through a skill, so a Smartthings hub may not be needed if the Echo becomes more of a hub.
The Echo is not a hub at all, nor is it likely to ever become one. In terms of its place in the home automation ecosystem, the Echo/Dot/Tap is nothing more than a voice interface to the Alexa service running on Amazon's servers. The Alexa service converts your voice commands into vendor-specific requests (based on which device(s) you're trying to control) that it then forwards on to the appropriate vendors' cloud-based services, which in turn convert that into a command that is sent either directly to your smart device(s) (if WiFi based) or to a hub in your home that then converts that request into a Zigbee, Z-Wave or other protocol command that it sends to the target device. The response then travels back through the same path, going through multiple conversions along the way, until your Echo/Dot/Tap is instructed to (hopefully) tell you, "OK".
The short version is that the Echo/Dot/Tap don't actually control anything, nor does the Alexa service. They just combine to act as a voice-based interface to the vendor-specific services that actually control your devices.
An alternative to the lighting hub would be the wi-fi bulbs like the $20 TP-Link ones. I can dim, but no color change.
And that's OK for just a few bulbs. But a hub-based solution eventually becomes more cost-effective (the exact break-even point varies based on several factors), and is yields far more functionality and flexibility.
Although I could get the color change down the road as a plug and play option. A smart switch is doable (and will come into play for something like a kitchen sink light) but I do not think the switch is the best option for the rest of the lights.
If you have lights that are already controlled by a wall switch you might find that, if your current wiring allows for it (you need to have a neutral wire for almost all smart wall switches to work), a smart switch is the way to go, for a couple of reasons: 1) You won't need to worry about people turning the conventional wall switch off and cutting power to smart bulbs. 2) If you have a non-dimming wall switch that controls at least 3 bulbs then you're already just about breaking even on initial hardware cost using a smart switch to control "dumb" bulbs vs using smart bulbs, and will generally be well past that point with 4 bulbs. For instance, I have a ceiling fan with a 4-bulb lighting kit. I use a GE Link fan control wall switch for the fan itself, and a GE Link dimming light switch for the lighting kit. The latter cost ~$40 at the time, and adding 4 standard LED bulbs @ $3 each (bought in multi-bulb packs) put the total cost at ~$52. Using dimmable smart bulbs...which were going for at least $15 at the time...would have cost $60, and still left me with a situation in which I had to make sure nobody every turned off the conventional wall switch. So the smart switch was the...well...smart way to go.