I don't think you can beat the Canon 100L macro. It's a great macro lens and many have said it is also a great portrait lens, so 2 birds with 1 stone, and there have been some deals at Amazon recently (at least for USA shoppers).
You mention landscape work, and one typically assumes wide angle. A 24-70 could fit the bill, or the 24-105.
Not too many "cheap" options for wider, especially if you want AF. The Tokina 16-28 comes to mind.
The Canon Price Watch alerts work if you have time.
I can get the 100L right now for $830 after rebate in Canada which is pretty good. I was looking at the Tamron but now not so much with the Canon price being what it is.
I'm just not super interested in a 24-70/105.
As I said, I have an RX100 in this range and it covers my walk-around, get whatever shots. I find I'm happier with a prime at around normal range or either side of it. I just take way better pictures that way and I do appreciate the wider apertures.
I'm not getting much feedback on lenses wider than 24.... people have said why don't you just shoot at 24, but fact is I want to shoot wider than that.... jury still out on UWA. I find 14mm (ie. Samyang/Rokinon) just too out there for me. Maybe there's a shortage of good lenses wider than 24 (for less than $2000)? Will nobody speak up for the 17-40? I want to shoot things at around 20mm