Actually, I just set this up last night.
I created a virtual on/off switch named garage door.
I created two routines. One was open garage door and the other was close garage door.
I tied them both to the virtual switch using Alexa helper.
I have Alexa access to the virtual switch.
It respond to “Alexa, open/Close Garage door”
Alexa responded to “open”/“close”? I thought only “turn on/off” was supported?
Officially, it’s Turn on/off and Switch on/off.
But many community members have reported success with all kinds of other words, from “commence” to “engage.”
All I can say is try it and see what happens. It doesn’t work for me, but my voice tends to slur somewhat and may be harder to parse.
It may also depend on exactly what device names you’re using.
Interesting! I just tried “Alexa, open deck lights” and my deck lights turned on. Similarly, “Alexa, close deck lights” turned them off.
Time to make a bunch of virtual switches for my doors! The tricky part might be keeping the virtual switches in synch with the actual door state. Or figure out how to make a virtual momentary on/middle/off switch.
I was able to do this successfully for a Virtual Switch “linked” to my Projector Screen. I wrote the Device Handler for Projector screen to handle up/down (but I also put in on/off) … I added the Virtual Switch for … hmmm… not sure exactly why, but I’ll dig up the code.
Sorry for my ignorance, but I am new to ST and Elexa. How do you create a virtual switch and routines? Are you doing this in the Alexa app, or ST app?
No worry… They are created in the ST app.
Follow this link… Tins of info here.
tflake, I was in the same situation as you just yesterday. See my post
This is the step by step FAQ.
The other topic people recommended was a troubleshooting thread set up to help one member who was having problems with his particular setup. It doesn’t use the regular method.
I would start with the FAQ first. 
just configuring mine… virtual switches no longer needed unless you want it to control more than one devices… direct smarthings ifttt can now turn switches on and off and lock unlock doors.
waiting for direct mode , routine, door/garage and door status options… 
I can’t wait to get status updates from echo… How nice will it be to ask the status of the garage door and she says it’s closed. Or ask if any Windows are open and she tells you which ones.
no kids anymore but would be cool to ask if presence sensor is home
also now that I merged my audible account with amazon… it is cool to listen to audio book on alexa and also on phone and have them sync…
There is now a direct connect with alexa through the Alexa App.
Go to settings/ connected home
Then to smartthings
Then authorize devices.
Then tell Alexa to discover devices
It can now see all switches and lights directly and you can also create and name artificial groups of devices.
No more virtual switches or tiles and no more ifttt needed.
It is also ligtening fast compared to going over ifttt.
No locks or door states and no direct color control but we are getting there.
It’s an excellent integration. The official announcement was in August. Many people in the community have been using it since then.
The virtual devices are only used when you want to control a device of a class that is not currently supported by Echo.
What’s new this week is that the same capabilities are now available for the Amazon fire TV voice remote.
Ya I read that and it us not real clear that there is direct control outside of ifttt… All the examples on this site seem to talk only about iftttt
Read the first post. It describes two completely different methods of integration. The first one uses the “Alexa, trigger kitchen lights” format which is using the Alexa IFTTT channel.
The second one uses the “Alexa, turn on kitchen lights” format which uses the smartapp method you mention in your first post here. No IFTTT.
Both have their uses. Both are detailed in the FAQ thread, including with screenshots.
The Second Official Integration: Connected Home Devices
The second method is an integration specific to SmartThings and echo. With this method, you will be able to group multiple devices together, such as a group of lights. You also won’t have to include the word trigger. Set up is a little more complicated, but straightforward.
Thanks …instead of turn on…xxxx I have found it better to say alexa xxx on. This is because once in a while it says…I cannot find device turn off xxx in you profile.
Whatever works for you.
To save somebody else the trouble. The FireTV remote is not compatible with the Echo, it can only be used with the Fire TV. I was under the impression that I could use the remote for both devices. That is not the case. You need different remotes to control the Fire TV and the Echo. I’m sure this was in the fine print somewhere but I missed it. That was actually the reason I ordered the Fire TV was to get the remote for the Echo. 
I didn’t realize at the time that Alexa was baked into Fire TV. So I ended up being both disappointed and happy.