Yes,you are right.

For example,when someone hold the door for you,you should use 谢谢。

when someone did a big favor for you which means a lot for you,you may use 感谢/多谢了

Based om experience:

感谢: it is more formal.

多谢了: It  a little informal. 

谢谢:  It is very normal. 

感谢vs谢谢：    1, 感谢 is more like a written word，谢谢 is more like a colloquial word.
                          2, 感谢 is more official and formal，谢谢 is more common  and often used in daily life.

感谢vs多谢了： 1.感谢 is more like a written word， 多谢了 is entirely a spoken word.
                           2, 感谢 is more official and formal，谢谢了 is more common  and often used in daily life.
                           3, 感谢 is a word， barely show up independently， 谢谢了 is a very spoken word，谢谢了 
                              can be used as a sentence as well.

感谢：1, as a noun, usually there's a phrase: "表示感谢"means show/express gratitude to someone, 感谢 is a noun in this phrase.
            e.g. 对你的帮助表示感谢。(I ) express my gratitude to you for your help.
            2, as a verb, usually used in phrase："感谢＋something/someone" 

                basically we use it before a noun which/who is the object you thank to. 
                e.g. 感谢你的邀请。 Thank you for your invitation.

谢谢：1，can be used independently as a sentence.   e.g. 谢谢。 Thanks.
            2，as a verb， usually used in the phrase："感谢+something/someone"  thank something/someone.

谢谢了：1, It‘s not a word but a phrase which is often used in spoken language.
                2, It can be used independently as a sentence in daily talk : "谢谢了" Thank (you).    

Thanks a lot

多谢了

Millions of thanks

万分感谢

Thank you so much

太谢谢了

Thank you very much

十分感谢，非常感谢

If you write 谢谢啦 instead of 谢谢了， then it might sound somewhat 'cute'. However both of the two mean Thanks