I thought the same, so many cars and tracks that they could have done iconic combinations.
A Aston Martin around Goodwood would have been a good one!
Alternatively, I'm hoping that to compensate in a way, the cars we're assigned to for each Circuit Experience has more to do with each track, rather than being almost entirely Gr.4/Gr.3 cars like in GTS. That is, barring the actually-relevant Porsche 919 for Le Mans.
In this regard, I'd pick the following cars for each venue:
Blue Moon Bay Speedway: Plymouth Superbird
Daytona Road Course: Ford GT LM GTE '18
Goodwood Circuit: Jaguar E-Type
Fuji Speedway: Lexus RC F
Nurburgring Nordschleife: Nissan Skyline GT-R (R34) Spec V Nur
Trial Mountain: Toyota Supra GT500 '97
Suzuka Circuit: Honda NSX Type R '92
Le Mans: Mazda 787B (Just to have a change, rather than having the Porsche 919 again.)
Interlagos: Gran Turismo F1500T-A
Red Bull Ring: Gran Turismo Red Bull X2014 Jr.
And so on.
EDIT: I had more ideas!
Sardegna - Windmills: Ford Focus RS '18
Fisherman's Ranch: Mitsubishi Lancer Evolution V GSR
Colorado Springs - Lake: Audi Sport Quattro S1 '87 (Y'know, since Pikes Peak isn't far from this location.)
Tokyo Expressway Central: Honda Fit Hybrid
Tokyo Expressway East: Nissan GT-R (R35) Premium
Tokyo Expressway South: Toyota GR Supra Racing Concept Gr.3
Sardegna - Road Track A: Red Bull X2014 Standard
Spa-Francorchamps: Peugeot 908
Brands Hatch - GP: McLaren 650S GT3
Autopolis: Nissan GT-R (R35) GT500 '16
EDIT2: Of course, we don't know how many variants of each course will actually be part of Circuit Experience, as many of them were not part of GTS' version of it. But I'm more than OK with a more curated list, with only a few venues having more than one layout available for Circuit Experience. I also appreciate that the trophy for Circuit Experience doesn't make you complete all available courses, but instead, simply 15 of them; the progress players needed for the GTS version of this trophy was different depending on how many courses had been added to GTS at the time. With additional tracks coming to GT7 after launch, it's nice to see that the number of courses we need to complete is static, rather than potentially changing (read: increasing) with updates.