My opinion

This option is better:

倫敦 (3)- 布魯塞爾(1)- 巴黎 (4) -(night train)- 威尼斯 (1) -佛羅倫薩(2) --->羅馬(3) I don't go 布魯塞爾 so I cannot comment on it. You can take away a few hours from 佛羅倫薩 time to go Pisa (1 hour train from 佛羅倫薩, many trains). You can go late afternoon to Pisa and come back 佛羅倫薩 in the late evening.

In Paris, I did not stay in hotel. Instead, I rent an apartment via 'www.vrbo.com'.

Xiong