I would a bit disagree on the comment concerning Chongqing and Chengdu food quality. Even though I admit this is highly subjective so I find food in Chongqing generally better (much better!) than in Chengdu.
I assume it has something in common with the city landscape and peoples attitude towards the life and work.
Even though Chongqing was till 1997 part of Sichuan the people’s behaviour is distinctly different than those in Chengdu. You may immediately realize that the life pace in Chongqing is general faster and more direct than in Chengdu – people are trying hard to succeed.
Also due to the mountain landscape the restaurants are generally closer to each other and therefore directly competing with each other what contributes to better food quality.
Nevertheless it’s fair to say that in Chongqing, similar to Chengdu, you will not be able to enjoy the variety of non Sichuanese food …
On top of that Western food in particular will be quite expensive. Generally in Kempinski there is Paulaner which is in average much better than Chengdu Paulaner and quite OK Thai restaurant.
For sushi you may go to Ying Li in Jiefangbei which is quite OK but I agree with Charlie that in average China does not really offer good sushi and sashimi (I would also agree that you need to really watch out for the quality!). In Ying Li there is also quite good Italian restaurant and as per my opinion the best Beijing duck restaurant in Chongqing and Sichuan :-).
Many Western restaurants are then in Tiandi and Hongyadong. But again – usually quite expensive and the taste differs from the one you are used to in the West.
In general if you really cannot eat spicy food I assume you will either spend quite an amount of money for average food or you will have to cook for yourself.
It will certainly not be an easy life for you in neither Chengdu nor Chongqing …