You have a lot going on texture-wise so I'd probably keep it simple in terms of rug texture or there'll be too much going on at once. Warm would do well in this room though, so that's good! You mention it's away from the light outdoor area, is this photo an accurate representation of the lighting you normally get in this room? So in summary, you might want to have a look at rugs that don't have much texture, and are a bit brighter in colour to help brighten up the room. Below are just a couple of examples of rugs that could work, and one more neutral example.

The most kid and pet friendly couch material is leather. So far our blue leather couch has coped with 18 years of toddlers falling asleep and weeing on it, cat vomit, Easter eggs melting between the cushions, spilt milk, spilt orange juice, spilt red wine, spilt coffee, and muddy dog paws. It just wipes clean. Our white leather chair is just as durable and is now 24 years old and just starting to look grubby. So go with beige or cream if you want. It would be a lovely choice, just make sure it is leather. Black or mid or dark brown would also look lovely with that beautiful rug but I think lighter colours would look fresher. Don't be at all scared to use light coloured leather.

I can really recommend the Danish brand "Rug Solid, which have rugs made totally out of recycled materials. This is a photo from our living room, where we have a recycled cotton rug from "Rug Solid". http://rugsolid.dk/en/

$300k would be the building budget only and will often not include the architect or other professional service fees like surveyors, engineers and certifiers. The biggest point to remember, is the reason behind engagement of an architect. Are you after a great lifestyle outcome in your home. Are you are detailed person wanting to ensure there is a place for everything in your home. Does your site offer something where you can gain by tremendiously. Do you want your own ideas challenged. The fees set by different architects are yes based around scope of service but also based around their skills and so not all architects do charge the same rates. My own service is for the building architecture, interior design and landscape design, you might say what does that have to do with my lounge room extension and in your case there maybe only interior scope or your external spaces maybe also impacted. My services also includes external real costing work from a cost planner, so you'll know how much your project will be very soon along he steps the delivery process. My service includes project management and my services covers off on a huge range of sustainable and passive design principles which are applied to my clients projects for best outcome. This is why architects fees can vary between providers. It is your lifestyle outcome that is at stake, Once you have spent the money you need to live with it or sell so ensure you factor in the gain in your assessment of fees . Be careful even though some architects have alot of positive reviews this does not mean their design ideas and direction are going to be best for you. Just agreeing with a clients thoughts is not helpful to a client. I charge on a combination of square metre and hourly service and percentage only on request by my clients. $3000 per sqm mention above is mid standard not high spec finish . But standard is subjective as well so this must be worked through with your architect.