Valencia is a fantastic place although being too hot in July and August.

Explanation: "Although" is used here because it's introducing a contrast between the fact that Valencia is fantastic and the fact that it gets too hot in July and August. The phrase that follows "although" must be a clause, so "being" would be incorrect. The correct sentence would be: "Although it is too hot in July and August, Valencia is a fantastic place."

Cars are very useful in the city though they are expensive.

Explanation: "Though" is correct here because it's used to introduce a contrast, and it is followed by a full clause ("they are expensive"). "In spite of" would be incorrect because it requires a noun or gerund after it (e.g., "in spite of the cost").