Why bother? Well, if your only goal is to see the lava, then yes, you'll want to go at night and a trip that can't include an overnight stay wouldn't be worth it. But even then, isn't it still hit or miss that you'll actually see something (might be cloudy)?

But if you're interested in more than just seeing lava, the Big Island has other things to offer. I did a day trip to the Big Island knowing that seeing lava wasn't in the cards and I sure don't regret it. We took the first flight in and rented a Jeep. First stop was the market in Hilo. Then drove north to Waipio Valley stopping and hiking around at one of the waterfalls along the way. After Waipio we turned around to head back toward Hilo and had lunch and walked around in one of the small towns. We drove back through Hilo and up to Volcano NP. We drove around the crater rim and got out at several points to hike around. It might just be "black lava fields" but if you haven't seen them before it's like you're on Mars or something. We thought it was really cool even if we didn't see lava. Plus, the Big Island just has a much different feel than Oahu and it was nice to experience that.