When we think of the meaning of the word "Sukkoth", what comes to mind is the actual Sukkah that we sit in. However, Rabbenu Bahya says the word "Sukkah" comes from the verb "to see". As we know, Sara Immenu, 'a"h, had another name, mentioned only once in the Torah, "Yiskah". Our Rabbis explain that it come from the word "to see".
In the case of Sara Immenu, 'a"h, it means she was able to see things in Ruwah Haqqodesh and prophesy. Another explanation is that she was so beautiful that everyone would look at her beauty. If so, what is the connection between Sukkoth and seeing? In truth, there is much we can see and much we should look at in order to understand the meaning of the Holiday of Sukkoth.
Yom Kippur is just over and we feel we are pure, that we cleansed ourselves. We feel that we are connected to Haqqadosh Barukh Hu. This is exactly the time where we are fit to feel great joy and happiness. The reason is because when we distance ourselves from all the physical distractions and temptations of the world and are able to purify ourselves, that is the time we are able to really connect to G-d and feel the closeness to Him. This is the recipe for true Simha and happiness.
The world tells us the opposite. When you are depressed they say we should go to the mall and buy yourself a dress. "You'll feel so much happier", they say. "The more you possess, the happier you will be!".
Sukkoth tells us the exact opposite. Sukkoth tells us that happiness is spirituality. The closer you are to G-d, the happier you will feel. It is the time that we leave our homes and we go dwell in the Sukkah. When I grew up, they built a Sukkah by taking sheets and tying them up. Nowadays, if you look at newspapers, you see the most amazing Sukkoth. Maybe this is a little bit of the Yeser Hara' manifesting itself even during holiday of Sukkoth. But even the fanciest Sukkoth that they sell nowadays cannot be compared to our homes.
This is the time Hashem tells us: "Do you want to feel real happiness? Come close to Me!".