Kelowna or Kamloops
 

We will driving from Vancouver to Banff during mid May. We are planning to stop half way and stay overnight. Which one between Kelowna or Kamloops should we stop over? Which one nicer? Any one has ever stay at Sun Peaks Resort Hotel. Any advices would be appreciated. Many thanks.

In my opinion, Kelowna is in a much prettier setting than Kamloops. It is on Lake Okanagan, there are beaches and wineries and orchards etc., as well as lots of variety in terms of accommodation because it is geared more to tourism than Kamloops (which is more of an industrial - logging - town).

Kelowna for a prettier location.
The Okanagen Valley is nice, whole thing.

I've been to Kamloops many times, and skied at Sun Peaks once. Can't tell you about the Resort Hotel, but it's a an hour-or-so detour from Kamloops.

Kamloops is on the Trans-Canada, and just east of the "top" of Coquihalla. So, that's a faster route between Vancouver and Banff than going through the Okanagan. But like other's said here, there's really not much there.

Kelowna is a happening resort city in the summer time. The beaches are crowded and traffic is horrid. Thereare great restaurants and lots of great wineries to check out. It is a far nicer city stay than Kamloops is, but Sun Peaks is a fabulous mountain resort in the summer time. Much like a small scale of Whistler. The Golf course is great and there is lots of other recreation options. Hiking, Mountain Biking, Tennis and a great outdoor swimming pool.
There are a number of hotel options at Sunpeaks from Hotels to Condos, to private chalet rentals.
Choose either Kelowna or Sun Peaks depending on what type of a stay you want, and stay longer than 1 night, but skip Kamloops. If you want a stop on the highway, you might want to consider Salmon Arm instead, as it is on Shuswap Lake.