Grammatically, "〜たいです" is correct. However, in daily conversations, "〜たいのですが、、、" is more common (and convenient).

Let's say your friend asks you what you want to do in Tokyo, you could say, "おいしい寿司が食べたいのですが、、、(I'd like to eat good sushi...)" or "秋葉原に行きたいのですが、、、(I'd like to go to Akihabara.."

By adding "〜たいのですが、、、" instead of affirmative "〜たいです。", you leave the conversation open for the other person to offer the next move/step/option.

"〜たいのですが、、、" infers the following, for example, and it is up to the other speaker to decide what to do or how to help you. (I'd like to eat good sushi...) I have no clue where to go. (I'd like to eat good sushi...) I'm not sure if I can afford it. (I'd like to eat good sushi...) I wouldn't know what to order.

I hope this helps.

Well it sounds like you already know how to express a desire to do something using the suffix -たい. Saying something like 食べたい or 見たい is sufficient albeit a very formal way of expressing your desire to do something. Im not sure but it sounds like you want the word for word equivalent in Japanese, if thats the case then you would say for example "私は食べたいです.", literally "I want to eat." Now, in Japanese its not necessary to specify the subject in a situation like this. In saying just the verb with the suffix -たい it is understood that you are wanting to do something even when omitting 私-I and は-topic marker. Although I would suggest you add です at the end to make it sound more polite. Hope that helps! -_^