First of all, "landscape" does not describe the kinds of images that YOU might want to make. I use any and all focal lengths at my disposal for making different types of "landscape" images. Some are close in. Some are tightly framed shots of scenes in the distance. They vary all over the map. No one lens would ever do what I need for "landscape" photography.
Likewise, "group shots" does not effectively describe what you're looking for. Three people photographed with the camera just a few feet away is an indoor group shot as is a shot of 75 people in a larger venue with the camera 50 feet away. Each calls for significantly different lenses to do well.
The bottom line is that you (as well as anybody else asking this sort of question) need to describe to us the images that are in your mind (precisely the types of things you want to photograph, distances involved, etc.) before we can give you any truly sensible suggestions for lenses to buy. In other words, you need to describe precisely what YOU mean by "landscapes" and "group shots". Other people's definitions could easily differ enough to require totally different photo equipment.
Well check my sig, i already have a 70-200 so that covers tight/isolated landscape shots.
What is missing from my gear? a wide angle to u know shoot landscape in a wide angled view.
In terms of group shots, a group of 3 people can be taken with a nifty fifty indoors, again check my sig
So u want me to be specific? well lets see. i want to shoot indoors in a party, could be a house party or it can be a large hall with maybe say 10-15 max in a bog standard house(do i need to tell u the size of the house? whats inside? address? lol).
I want to shoot wide angle landscape capturing lots of things in the frame. i also want to take ****s of architecture buildings where its difficult for me to step back away from the frame to get more in frame(when using something like a nfity fifty).
Is that not specific for you? i do know that there are different kinds of landscapes and different indoor shots when you nip picking but people can easily help a person out when they are looking for a landscape lens to shoot wide and a lens that can be used for indoors/group shots.
You really do not need to know how many people invovled in the pic indoors(how can u pre define that unless u are a pro shooting a wedding and know whos coming and the venue?) And u really dont need to ask a person who already has a tele lens, what kind of landscape they want to take on their new lens. not a isolated shot as that person(me) already has a lens to do that and quite a darn fine one too