As the street was getting more and more crowded, it was harder for us to drive home.
→ The more crowded the street got, the harder it was for us to drive home.

I think I'm getting a cold because of the unpredictable weather.
→ I think I'm coming down with a cold because of the unpredictable weather.

It took us more than 3 hours to discover the inner Hanoi.
→ We spent more than 3 hours discovering the inner Hanoi.

We spent.
→ We spent a lot of time planning the trip. (For this sentence, you might need to provide more context for a complete sentence.)

Why don't you consider our suggestion before making an official decision?
→ I suggest you consider our suggestion before making an official decision.

Watching TV is not as important as doing homework.
→ Doing homework is more important than watching TV.

Doing homework.
→ Doing homework should always come first before watching TV. (The sentence seems incomplete, so I've added context.)

My friend plays the piano brilliantly.
→ My friend is a brilliant pianist.