My opinion

This option is better:

伦敦 (3)- 布鲁塞尔(1)- 巴黎 (4) -(night train)- 威尼斯 (1) -佛罗伦萨(2) --->罗马(3) I don't go 布鲁塞尔 so I cannot comment on it. You can take away a few hours from 佛罗伦萨 time to go Pisa (1 hour train from 佛罗伦萨, many trains). You can go late afternoon to Pisa and come back 佛罗伦萨 in the late evening.

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

Xiong