oh man, I totally feel u on this. I've been using the a7 IV for a year now and went through the same struggle!! For travel and family stuff, weight actually matters more than people think when you're carrying it all day. Here's my take based on my experience: 1. Sony FE 24-70mm F2.8 GM II: Honestly, it's the best. The AF is literal magic for tracking kids or pets in video. It's super light for what it is, but yeah... that price is steep.
2. Tamron 28-75mm F2.8 Di III VXD G2: This is what I usually recommend if you wanna save cash. It's tiny and the G2 optics are actually great. I miss the 24mm sometimes for landscapes, but it's not a dealbreaker??
3. Sigma 24-70mm F2.8 DG DN II Art: Great middle ground for sharpness, but it feels a bit heavier in the hand after a few hours of walking. Tbh, that extra 4mm is nice for tight indoor family shots, but for outdoors? Maybe not worth the extra $1k... gl!!

Hmm, I've had a different experience. I know everyone says you NEED f/2.8 for everything, but for travel landscapes and family videos on the a7 IV, I think the focal range actually matters more than the aperture? - Seriously check out the Sony FE 20-70mm F4 G. It's way LIGHTER than the GM and having 20mm on the wide end is basically a cheat code for landscapes and vlogging. - The Tamron 28-75mm F2.8 Di III VXD G2 is a decent option for the price, but 28mm is kinda tight for indoor videos imo... you end up backing into walls lol. - I tried the Sigma 24-70mm F2.8 DG DN Art but it's SO heavy... idk if I'd want that on a neck strap all day honestly. The a7 IV handles low light so well that f/4 usually works fine for most family stuff anyway. Plus you save a ton of money! hope that helps anyway 👍

TL;DR: The Tamron 28-75mm F/2.8 Di III VXD G2 is the best value at ~$750. Check out the Camera Size website to compare footprints. I’ve used both for years, and honestly, I'd suggest being careful with that Sony FE 24-70mm F2.8 GM II price—it’s amazing, but maybe overkill? ur basically paying double for 4mm. Tbh, the Tamron is plenty sharp for family stuff. Gl!

I have to respectfully disagree with the idea that focal range is the only deciding factor here. From a market analysis perspective, the real value is often hidden in the AF actuator tech and the proprietary handshake between the glass and the body. I spent a lot of time researching this before I landed on my current setup. I initially went with a popular third-party alternative to save money, thinking the optical quality was close enough. But in real-world usage, especially for family videos, I found that the third-party AF often struggled with the a7 IV's more advanced tracking modes. I learned that the native lenses simply have better throughput for the body's autofocus algorithms. Eventually, I realized that features like focus breathing compensation and linear response manual focus were more important for my hybrid workflow than just saving a few hundred bucks. Basically, ur paying for the reliability of the system integration. Tbh, I found that the mid-range native options often provide the best balance for a daily driver without needing to jump to the top-tier professional lines. It really changed how I approach my travel kits. (at least thats what worked for me)