Hey,
Great to hear you’ll be in Hong Kong this summer! A day trip to Guangzhou is definitely possible, and it’s pretty straightforward, too. The high-speed trains between Hong Kong and Guangzhou are super quick—just around 1 hour from Hong Kong West Kowloon Station to Guangzhou South Station. You’ll have plenty of time to explore the city in one day.
As for whether it’s worth it, it really depends on what you're into. Guangzhou is a big, bustling city known for its amazing food scene (especially Cantonese dim sum and street food), beautiful parks, and historical spots like the Chen Clan Ancestral Hall or the Canton Tower. If you enjoy exploring different parts of Chinese culture and getting a taste of the local lifestyle, I’d say it's totally worth it! That said, it’s best to plan your time carefully if you’re just doing a day trip, as the city is pretty spread out. I’d recommend choosing one or two key attractions to visit, especially since the travel time adds up.

If you’ve got more time in Hong Kong, I’d also recommend staying overnight in Guangzhou to really soak it all in, but if you’re short on time, a day trip will definitely give you a good taste of the city! Let me know if you need any tips on what to see or how to get around! Cheers,