Ok, so I went through the process of upgrading last year in anticipation of a trip to Walt Disney World in Orlando, FL. 10 days, wife, 4 kids, wife's parents. I had a K200D, but we budgeted an upgrade to the K-5ii as part of the cost of the trip. So this was my kit at WDW, and I'll kind of review things as I list them.
1. Pentax K-5ii. What can be said about this that hasn't already been said? Great at near-dark/pitch-black levels. This was the perfect travel camera for me. I slapped the DA 40 on there, set the mode to Av to control dof, shot in JPEG cuz I knew I'd be shooting a lot. In fact, I shot 3,300 images. Yikes! One awesome thing: I bought a mini-usb to hdmi connector, and I believe the K-5ii comes with the mini-usb to rca connectors (or maybe I bought those too). At night, after the day in the park/s, as we cleaned up and were exhausted, I plugged the camera into the tv and began the slide show of the day's shots. It was a great way to relax without the distraction of the TV, and it was a great way to relive the moments of the day.
2. DA 18-135. Hated HATED this lens for several reasons. 1. It's freaking huge! 2. It's freaking heavy. 3. It's not sharp in most shooting circumstances. Even outside with ISO to 80 and aperture above 7 or 8, it was still not as sharp as the DA 40. 4. In the hot, humid environment of FL, we left the hotel around 8am (it was already quite warm and muggy), jumped on a cold, air-conditioned bus for a 30 min. ride to the park, got out, unzipped the bag with the 18-135 to snap shots as we enter the park, the darn thing would be fogged over. Switch to the DA 40, no fog, no problems. That 18-135 would take HOURS to defog. I don't know if it's all the glass and elements or what, but it was super-frustrating, especially for a $400 lens that is supposed to be WR. I sold the 18-135 as soon as we got home.
3. DA 40mm Ltd. LOVE this lens. This stayed on my camera 95% of the time for several reasons: 1. It's light. 2. It's super-compact. 3. It's sharp, much much much sharper than the 18-135 even using the exact same camera settings. Of course, it won't get as wide as the 18-135. But when I wanted something zoomed in, this lens was so sharp that I could zoom in during post-production. In fact, the 40mm zoomed in/cropped was much much much sharper than the 18-135 non/cropped.
4. Clik-Elite Probody Sport. I love, LOVE this bag. Comfortable straps, the waist strap really helps support the load. Integrated hydration bladder meant always having water and NOT paying $7 for a bottle of water. The bladder never sweated into the storage compartments. Plenty of room for my lenses, batteries, and sdhc cards. I had a local shoe repair shop sew daisy-chains to the shoulder straps. I used a Think Tank backpack camera mounts, and that was super-awesome: camera always right at my chest. I didn't have to have it in my hand all the time. It was evenly supported across both straps, so I never felt the weight of the camera, unlike a messenger bag or sling strap (both of which I have, and my neck begins to hurt after an hour).
5. Extra non-OEM battery that I purchased from China off ebay. This functioned great. Never let me down. Always charged both batteries at night. I didn't shoot too many videos, but when I did shoot video, the video really drained the batteries (both the Pentax OEM and this Chinese one).
6. Several hdsc cards, two 32gb cards.
So I go against the others here who automatically suggest the 18-135. For the price, I think there are better lenses. Maybe none are so flexible as the 18-135, but none so soft either. I recommend the DA 40mm Ltd. A few months ago, I added the F 35-70 and F 80-200 to my bag. These replaced the 18-135 as well as the "kit" 18-55 and 50-200. I found that I rarely shot wider than 35mm, or 40mm actually, and I really hated the shots at 18mm. These specific F lenses are nearly as sharp as the DA* lenses when stopped down 2-3 stops with moderately low iso. In other words, I would pit these two particular F lenses against my DA 40mm LTD and DA 70mm LTD and any DA* lens when shooting outside on a bright day with a low ISO, small aperture, and high shutter speed. And for the price? What a bargain!