Track wishlist, with most/all tracks having time and weather, and any additional layouts listed afterwards. Original Gran Turismo tracks will all include an unmentioned reverse variation:
From GT1-5 and TT-
Apricot Hill
Autumn Ring full course , Autumn Ring Mini
Cape Ring full course, Inside, Periphery, North, South
Chamonix full course, Mini, East, West
Circuit de Valencia full course, Inside, Outside (Don't know proper layout names)
Deep Forest Raceway
Driving Park: Beginners course, no chicane (oval)
Complex String
Test Course (replaced by the oversized SSRX)
Eiger Nordwand short course, G trail, K trail, W trail
Fuji Speedway F, GT, '74-'85, '93-'04 ('65-'73 and '86-'92 possible)
Grand Canyon dirt course, road course, mini
Grand Valley full course, East
Grindelwald
High Speed Ring
Infineon/Sonoma/Sears Point Sports car course, stock car course, bike course (to be used by WTCC this year, so could be included)
London, Long (Fairly sure this was talked about before GT5's release, but wasn't heard of since)
Circuito de Madrid full course, mini
Mid-Field Raceway
New York
Pikes Peak Hill Climb
Red Rock Valley Speedway
Rome (Current), GT2-GT3 version, GT2 short version, Rome Night
SSR5
SSR7 (only if pits are added)
SSR11 (GT3), GT1-2 version (seen in screenshots for GT2)
SSRX Oval, possible road course but has incomplete banking
Seattle full course, short
Spa, (would like to see the old bus stop)
Smokey Mountain East, North, South, West
Super Speedway
Suzuka Circuit full course, east, west, (Would like to see the original, which has no chicane at the end, Degner as a single corner, a slightly tighter 130r, a faster/smoother Dunlop curve, and the second left-hander in the esses is slightly tighter)
Swiss Alps
Tahiti Maze
Tokyo R246
Trial Mountain
Twin Ring Motegi Oval, full, east, west
El Capitan
Indianapolis Motor speedway oval, road course (GT5 road course and the newer road course)
Daytona Oval, road course
Monza (current), (would like to see the unchicaned circuit+oval with the original faster Lesmo corners and Parabolica. The oval also has optional chicanes that would work nicely with the current circuit layout. Also want the oval by itself.)
Tsukuba full, short
Laguna Seca
Circuit de la Sarthe 2005, 2009, both with and without chicanes (maybe add some older layouts too, and the Bugatti circuit)
Nurburging GP track, GP/D, Nordschleife, 24H, Type V, other unmentioned possible layouts.
Top Gear Test Track
Code d' Azur
Toscana
Then tracks I'd like that haven't yet been in GT or TT:
Bathurst (scanned for a future game). Hopefully also has the track without The Chase.
Brands Hatch GP circuit and Indy circuit. Possibly the Rallycross track.
Silverstone and it's many possible variations.
Watkins Glen with and without The Boot, + with and without the chicane.
Donington Park GP circuit and National circuit.
Oulton Park International Circuit, Island circuit, Fosters circuit
Rockingham Motor Speedway (UK). Has an oval and many possible road course variations inside of it.
More F1 circuits (past and present), such as Imola, Melbourne, Montreal, and Hockenheim (current track, old track with and without chicanes and the stadium section)
Lausitzring- Grand prix circuit, short circuit, Tri-oval, Oval, Long distance cicuit.
More ovals of varying size and type, including any road course variations they have: Bristol, Pocono, Atlanta, Charlotte, Darlington, Fontana, Martinsville, etc
Some IndyCar circuits such as Barber and Long Beach.
As for cars, I'd like GT6 to have more NASCAR (sprint cup, nationwide, trucks). If GT6 has a livery editor and PD can't license the individual cars anymore, they could do what Forza has done with the cars and have the unliveried versions that you then add to yourself. I would also like IndyCar and Indy Lights to be included, possibly some more F1 cars if they can be licensed, BTCC, and WTCC.
If PD can get the TOCA license then they may be able to have the Porsche Carrera Cup cars included (a way around the Porsche license?), along with BTCC and the Ginettas. PD also wanted the GT1 license for GT5 but ran out of time, so this may come in GT6. Hopefully PD uses their licenses better this time around.
Finally, GT5 premiums should all carry over to GT6, along with near-premium standards. As for other cars, I'll leave that to everyone else...