No idea about the second two but for the Piano Concerto i would definetly suggest the Living Stereo SACD of the Van Cliburn recording.

It is available on Amazon for around $10 last time i checked

I browsed at Arkivmusic. The only SACD version of the Barber appears to be on a Telarc SACD called Transmigration, with the Atlanta Symphony under Robert Spano. Haven't heard it.

There are two listings for the Rodrigo. I am pretty sure that both of them are out of print. One is on a Sony non-hybrid SACD called Spanish Concertos, with John Williams guitar. It's described as "Special Order."

The other is a Mercury recording with the Romeros and the San Allessandro Symphony. It's described as back-ordered, but these Mercury SACDs have been out of print for years.

On the Tchakovsky, I like the classic Van Cliburn reading, too. Sound is a little dry. It's either 2- or 3-channel, but not surround sound. Another SACD that has gotten good reviews is Sudbin, Neschling, Sao Paolo (BIS). There are a couple of other SACD versions (Volodos, Lang Lang, Lugansky) that I haven't heard anything about.