I've been HAPPILY using Guitar Tracks Pro 4 for several years and have recorded a lot of material! I just upgraded my laptop to Win10 64-bit. Guitar Tracks Pro 4 works great, but I just upgraded from Amplitube 2 to Amplitube 4. I CANNOT get Amplitube 4 to show up as a VST in GTP4. Anyone have any suggestions?  Is there an inexpensive upgrade path to Sonar that will will import my GTP4 files, and will Sonar work with Amplitube 4?  Thanks in advance.

Amplitude 4 is 64 bit only, Guitar Tracks Pro 4 is 32 bit and might not load 64 bit plug ins. I cant really say for sure.
I know that Guitar tracks 4 is only supported up to Windows Vista. so there's another fish in the barrel.
have you made sure to put the Amplitude DLL in the VST folder that scans the plug ins ? or point to it using the plug in scanner ?
 
If not I would try a demo version Sonar or purchase something like Sonar Home studio.
https://www.cakewalk.com/Products/SONAR-Home-Studio
I believe its only 34.99 on sale right now.
 
It also includes a base version of TH3 as well. which is another monster Guitar Simulator. 
 
 

GTPro qualifies you for the current Cakewalk customer upgrade path.  You can open your GTPro 4 projects in Sonar (I started with GT Pro 3 way back in the day and my original projects open just fine in Sonar except that I don't have some of the original plug-ins I used back then.)
 
I would expect home studio would also open GTPro projects, but you might try the demo first (if one is available.)

Unfortunately the only free trials Cakewalk is offering is the 3 versions of Sonar. (Artist, Pro, Platinum).
https://www.cakewalk.com/Products/SONAR/Try-SONAR
Home studio is only 34.99. Its almost a no brainer for that price. 
 
6 years ago you could touch any version of Sonar for under a 100 bucks.
This price is impressive.

Thank you everyone for your answers.  I got a Cyber Monday coupon from Guitar Center, so I'm able to get Sonar Artist for $85.00.

glpsfass
Thank you everyone for your answers.  I got a Cyber Monday coupon from Guitar Center, so I'm able to get Sonar Artist for $85.00.

It is $1 less at Audiodeluxe  once you create an account and put it in your cart.